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Priya, Prabhu. "The Impact of Los Angeles Wildfires on Particulate Matter Concentrations and Public Health: A 2023 Analysis." International Journal in Engineering Sciences 2, no. 2 (2025): 18–21. https://doi.org/10.5281/zenodo.14888045.
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Wildfires in Los Angeles have become increasingly frequent and severe due to climate change, significantly affecting air quality and public health. This study investigates the connection between wildfire events in 2023 and concentrations of particulate matter (PM₂.₅ and PM₁₀), utilizing data from the California Air Resources Board (CARB) and the South Coast Air Quality Management District (SCAQMD). The findings highlight the correlation between wildfire emissions and PM spikes, with a focus on the health implications for Los Angeles residents. The research highlights the necessity for focused strategies to reduce health hazards during wildfire seasons.
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Adelaine, Sabrina A., Mizuki Sato, Yufang Jin, and Hilary Godwin. "An Assessment of Climate Change Impacts on Los Angeles (California USA) Hospitals, Wildfires Highest Priority." Prehospital and Disaster Medicine 32, no. 5 (2017): 556–62. http://dx.doi.org/10.1017/s1049023x17006586.
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AbstractIntroductionAlthough many studies have delineated the variety and magnitude of impacts that climate change is likely to have on health, very little is known about how well hospitals are poised to respond to these impacts.Hypothesis/ProblemThe hypothesis is that most modern hospitals in urban areas in the United States need to augment their current disaster planning to include climate-related impacts.MethodsUsing Los Angeles County (California USA) as a case study, historical data for emergency department (ED) visits and projections for extreme-heat events were used to determine how much climate change is likely to increase ED visits by mid-century for each hospital. In addition, historical data about the location of wildfires in Los Angeles County and projections for increased frequency of both wildfires and flooding related to sea-level rise were used to identify which area hospitals will have an increased risk of climate-related wildfires or flooding at mid-century.ResultsOnly a small fraction of the total number of predicted ED visits at mid-century would likely to be due to climate change. By contrast, a significant portion of hospitals in Los Angeles County are in close proximity to very high fire hazard severity zones (VHFHSZs) and would be at greater risk to wildfire impacts as a result of climate change by mid-century. One hospital in Los Angeles County was anticipated to be at greater risk due to flooding by mid-century as a result of climate-related sea-level rise.ConclusionThis analysis suggests that several Los Angeles County hospitals should focus their climate-change-related planning on building resiliency to wildfires.AdelaineSA, SatoM, JinY, GodwinH. An assessment of climate change impacts on Los Angeles (California USA) hospitals, wildfires highest priority. Prehosp Disaster Med. 2017;32(5):556–562.
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Schoenberg, Frederic P., Chien-Hsun Chang, Jon E. Keeley, Jamie Pompa, James Woods, and Haiyong Xu. "A critical assessment of the Burning Index in Los Angeles County, California." International Journal of Wildland Fire 16, no. 4 (2007): 473. http://dx.doi.org/10.1071/wf05089.
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The Burning Index (BI) is commonly used as a predictor of wildfire activity. An examination of data on the BI and wildfires in Los Angeles County, California, from January 1976 to December 2000 reveals that although the BI is positively associated with wildfire occurrence, its predictive value is quite limited. Wind speed alone has a higher correlation with burn area than BI, for instance, and a simple alternative point process model using wind speed, relative humidity, precipitation and temperature well outperforms the BI in terms of predictive power. The BI is generally far too high in winter and too low in fall, and may exaggerate the impact of individual variables such as wind speed or temperature during times when other variables, such as precipitation or relative humidity, render the environment ill suited for wildfires.
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Mis. Teodora James Nyamahanga, Dr. Bhawana Thukral, and Mr. Idris Levi Mamman. "Adapting Food Systems and Nutrition Security: Los Angeles Wildfires in the Face of Climatic Change." International Journal of Latest Technology in Engineering Management & Applied Science 14, no. 4 (2025): 287–92. https://doi.org/10.51583/ijltemas.2025.140400030.
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Abstract: The recent wildfires around Los Angeles devastatingly point out the relationship between nutrition security and climate change, aggravated by the Santa Ana winds that dry out the region and increase the likelihood of wildfires at speeds of 60 MPH (96.5 KPH). These fires disrupt the agricultural supply chain alongside ecosystems, limiting access to a variety of food commodities and exacerbating the already existing food insecurity challenge. The wildfire impacts in Los Angeles are not just local, but part of broader phenomena observed during bushfires in Australia and within the Amazon rainforest, where rampant deforestation poses peril to biodiversity and vital activities like carbon sequestration. Wildfires cause long-lasting damage to food production and ecosystems when combined with fires, these put tremendous stress on global food sources, including Los Angeles. The farmer's perspective indicates the heightened dependence on local food systems drives home the reality of resilient food systems that will need to be built in Australia and the Amazon. Addressing sustainability and climate change with anticipatory adaptation frameworks based on effective land management practices are required to deal with the resilient challenges. Constructing sustainable diets and resilient food systems are vital for dealing with the consequences of climate calamities. Strengthening regional partnerships is the answer to ensuring food security, agriculture with climate smart agendas while protecting soil will do the trick.
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Schoenberg, Frederic Paik, Roger Peng, Zhijun Huang, and Philip Rundel. "Detection of non-linearities in the dependence of burn area on fuel age and climatic variables." International Journal of Wildland Fire 12, no. 1 (2003): 1. http://dx.doi.org/10.1071/wf02053.
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Evidence from Los Angeles County in California, USA suggests that the relationships between wildfire burn area and fuel age, temperature, precipitation, and fuel moisture are not linear. Instead, the relationships appear to have thresholds.The data seem to support the notion that fire risk is nearly constant provided various conditions are met: that fuel age and temperature exceed a given threshold, and that fuel moisture and precipitation are sufficiently low. There appears to be little distinction in terms of wildfire risk between conditions that are sufficient for wildfires and those that are extreme.
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Xu, Haiyong, Kevin Nichols, and Frederic P. Schoenberg. "Kernel Regression of Directional Data with Application to Wind and Wildfire Data in Los Angeles County, California." Forest Science 57, no. 4 (2011): 343–52. http://dx.doi.org/10.1093/forestscience/57.4.343.
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Abstract This article describes a method of kernel regression that can be used to investigate the relationship between a directional explanatory variable and a real-valued response variable. Cross-validation and bootstrap methods for obtaining sensible bandwidths and standard error estimates are also described. The proposed method is applied to wildfire and meteorological data from Los Angeles County, California, with the goal of summarizing and quantifying the impact of wind direction on the total area burned in wildfires ignited on a particular day. The results confirm that winds blowing from the northeast and east are associated with the ignition of wildfires of significantly larger burn areas than winds from other directions; the mean burn area of wildfires ignited on days with winds from the northeast is approximately 4.7 times that associated with the winds from the southwest. A major reason for this increase in burn area is confounding of wind direction with meteorological variables such as temperature, wind speed, and humidity, but even when generalized additive modeling is used to control for these meteorological variables, winds from the northeast are still associated with the ignition of fires of substantially larger burn areas.
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Cornwall, Warren. "In the ashes." Science 387, no. 6741 (2025): 1343–46. https://doi.org/10.1126/science.adx6890.
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Evan, Bah. "Case Study on Energy Strategy Concerning Santa Ana Wind Activity Triggering Fires in Southern California." Eksergi 20, no. 03 (2025): 68–70. https://doi.org/10.32497/eksergi.v20i03.6348.
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Santa Ana winds, which are characterized by their scorching, arid, and forceful surges, significantly exacerbate wildfire hazards in Southern California, extending to 23,000 ha, particularly in the Los Angeles region. The purpose of this study is to examine the correlation between anthropogenic influences and natural climatic phenomena, with a specific focus on the influence of regional energy policies on the frequency and intensity of wildfires. The interaction between the Santa Ana winds and landscapes that are becoming more flammable has become more intensive in recent decades, although they are a natural phenomenon. Inadequately regulated urban expansion, prolonged droughts, and elevated temperatures are the causes of this intensification. Utility companies explicitly link wildfire ignitions during wind events to their energy infrastructure, particularly above-ground power lines. Moreover, the crisis has been further exacerbated by inadequate utility modernization, delayed policy reforms, and limited investment in fire-resilient infrastructure. This study assesses the degree to which regulatory inertia and climate change interact to elevate the likelihood of wildfires by analyzing historical wildfire data, meteorological patterns, and the evolution of California's energy policies. In the face of escalating climatic extremes, the results underscore the urgent need for energy strategies that are forward-thinking and integrated and that prioritize environmental sustainability, conflagration prevention, and resilience.
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Korec, Daniel, Martin Blaha, Jiří Barta, and Jaroslav Varecha. "Innovative Approaches to the Use of Artillery in Wildfire Suppression." Fire 8, no. 6 (2025): 232. https://doi.org/10.3390/fire8060232.
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The increasing frequency and intensity of wildfires in hard-to-reach and hazardous areas represents a significant challenge for traditional firefighting methods. Wildfires pose a growing threat to the environment, property, and human lives. In many cases, conventional suppression techniques prove ineffective, highlighting the need for innovative and efficient solutions. Recent fires in the Bohemian Switzerland National Park in the Czech Republic; the Los Angeles area in California, USA; and the southeastern region of South Korea have underscored the necessity for alternative wildfire mitigation strategies. This article explores the potential of employing military technologies, such as artillery systems and specialized munitions, in wildfire suppression. The analysis includes a review of previous experiments, the research into non-standard methods, and an assessment of the risks and limitations associated with these approaches. Based on the research and simulations, it was found that one salvo (eight rounds) of fire-suppressant shells can cover up to 650 m2 of terrain with suppressant. Finally, this article proposes a direction for further research aimed at integrating military and civilian technologies to enhance the effectiveness of wildfire response. This work contributes to the ongoing discussion on the integration of artillery capabilities into crisis management and provides a foundation for the future research in this field.
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Sazzad, Sharif Ahmed, Redoyan Chowdhury, Md Rokibul Hasan, et al. "Public Health, Risk Perception, and Governance Challenges in the 2025 Los Angeles Wildfires: Evidence from a Community-Based Survey." Pathfinder of Research 3, no. 1 (2025): 26–41. https://doi.org/10.69937/pf.por.3.1.44.
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The January 2025 wildfires in Southern California, notably the Palisades and Eaton Fires, were among the most catastrophic in the state's history, leading to nearly 18,000 structural losses, extensive evacuations, and considerable public health repercussions. This study examines the social, psychological, and policy-related effects of these wildfires via a mixed-methods survey of 90 residents impacted by or near the events. Participants indicated elevated incidences of smoke-related health complications (52%), psychological discomfort (45%), and property or financial losses (35%), with several individuals demonstrating diminished faith in governmental response systems. Awareness of wildfire dangers was moderate; nonetheless, preparatory behaviours, such as establishing evacuation plans, were adopted inconsistently. Confidence in official communication was significantly diminished among historically marginalised populations. Nonetheless, a majority expressed a readiness to engage in community-driven mitigationefforts, encompassing educational programmes and Firewise USA techniques. The study's results correspond with and enhance current literature on climate-induced fire regimes, emphasising deficiencies in prevention-focused governance, mental health interventions, and risk communication. The statistics further underscore the importance of including Indigenous fire stewardship and locally informed preparedness strategies. This research provides timely, community-based evidence to enhance wildfire resilience strategies and facilitates a shift towards more equitable and adaptive fire control systems in California and other high-risk areas.
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Fallik, Dawn. "How Are Los Angeles Neurologists Faring With the Wildfires?" Neurology Today 25, no. 3 (2025): 1,7–7. https://doi.org/10.1097/01.wnt.0001098732.51443.c2.
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Rolinski, Tom, Scott B. Capps, and Wei Zhuang. "Santa Ana Winds: A Descriptive Climatology." Weather and Forecasting 34, no. 2 (2019): 257–75. http://dx.doi.org/10.1175/waf-d-18-0160.1.
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Abstract The criteria used to define Santa Ana winds (SAWs) are dependent upon both the impact of interest (e.g., catastrophic wildfires) and the location and/or time of day examined. We employ a comprehensive definition and methodology for constructing a climatological SAW time series from 1981 through 2016 for two Southern California regions, Los Angeles and San Diego. For both regions, we examine SAW climatology, distinguish SAW-associated synoptic-scale atmospheric patterns, and detect long-term, significant SAW trends. San Diego has 30% fewer SAW days compared to Los Angeles with 80% of SAW events starting in Los Angeles first. Further, 45% of San Diego SAW events are single-day events compared to 35% for Los Angeles. The longest duration event spanned 16 days for Los Angeles (27 November–12 December 1988) and 8 days for San Diego (9–16 January 2009). Although SAW-driven fires can be large and devastating, these types of fires occurred on only 6% and 5% of SAW days for the Los Angeles and San Diego regions, respectively. Finally, we find and investigate an extended period of elevated SAW day count occurring after 2005. This new climatology will allow us to produce month- and season-ahead forecasts of SAW days, which is useful for planning end-of-year staffing coverage by the local, state, and federal fire agencies.
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Lyerly, Eric. "Disaster planning for individuals with disabilities." Disability Compliance for Higher Education 30, no. 8 (2025): 1–4. https://doi.org/10.1002/dhe.31918.
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In the last year, natural disasters have devastated many parts of the U.S., ranging from hurricanes in Florida and North Carolina to flooding in the Northeast to wildfires in Los Angeles. Disaster response after such events often rightly focuses on addressing hazards, repairing infrastructure, restoring electricity, and mitigating further damage to affected regions. However, individuals with disabilities frequently face inequities before and after natural disasters and may not receive adequate support in such events.
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Senn, Savanah, Sharmodeep Bhattacharyya, Gerald Presley, et al. "The Functional Biogeography of eDNA Metacommunities in the Post-Fire Landscape of the Angeles National Forest." Microorganisms 10, no. 6 (2022): 1218. http://dx.doi.org/10.3390/microorganisms10061218.
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Wildfires have continued to increase in frequency and severity in Southern California due in part to climate change. To gain a further understanding of microbial soil communities’ response to fire and functions that may enhance post-wildfire resilience, soil fungal and bacterial microbiomes were studied from different wildfire areas in the Gold Creek Preserve within the Angeles National Forest using 16S, FITS, 18S, 12S, PITS, and COI amplicon sequencing. Sequencing datasets from December 2020 and June 2021 samplings were analyzed using QIIME2, ranacapa, stats, vcd, EZBioCloud, and mixomics. Significant differences were found among bacterial and fungal taxa associated with different fire areas in the Gold Creek Preserve. There was evidence of seasonal shifts in the alpha diversity of the bacterial communities. In the sparse partial least squares analysis, there were strong associations (r > 0.8) between longitude, elevation, and a defined cluster of Amplicon Sequence Variants (ASVs). The Chi-square test revealed differences in fungi–bacteria (F:B) proportions between different trails (p = 2 × 10−16). sPLS results focused on a cluster of Green Trail samples with high elevation and longitude. Analysis revealed the cluster included the post-fire pioneer fungi Pyronema and Tremella. Chlorellales algae and possibly pathogenic Fusarium sequences were elevated. Bacterivorous Corallococcus, which secretes antimicrobials, and bacterivorous flagellate Spumella were associated with the cluster. There was functional redundancy in clusters that were differently composed but shared similar ecological functions. These results implied a set of traits for post-fire resiliency. These included photo-autotrophy, mineralization of pyrolyzed organic matter and aromatic/oily compounds, potential pathogenicity and parasitism, antimicrobials, and N-metabolism.
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Beck, Steven, David Stoker, James Hecht, and Richard Walterscheid. "Backscatter Lidar Observations of Lower Tropospheric Dynamics during Southern California Wildfires." Journal of the Atmospheric Sciences 66, no. 7 (2009): 2116–24. http://dx.doi.org/10.1175/2008jas2890.1.
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Abstract Wavelike features suggesting gravity waves were revealed by lidar observations (from El Segundo, California) of smoke layers produced by large wildfires in the Southern California region during a Santa Ana event. Unique features of the observations were multiple thin layers that enabled precise determinations of wave frequency, amplitude, and vertical structure. The data revealed persistent wavelike oscillations that showed no phase variation with altitude, an amplitude of 20 m, and a period near 12 min. The observations were averaged over 1.5 min with a vertical resolution of 3 m and were obtained over a period of 5 h on 25 October and 8 h on 26 October 2007. Vertical profiles of temperature and winds from the Aircraft Communication Addressing and Reporting System (ACARS) of commercial aircraft departing Los Angeles International Airport (LAX) were selected for temporal and spatial coincidence with the lidar observations. In addition, satellite images of the smoke distribution over the Los Angeles Basin and the coastal areas (including coastal waters) to the south were obtained from Moderate Resolution Imaging Spectroradiometer (MODIS) data from overflights 5.5 h prior to the lidar observation window. The images show wavelike features with horizontal wavelengths of ∼10 km or less. The temperature data showed an inversion layer topped at 500-m altitude. The wind data were consistent with a residual sea breeze near the surface and Santa Ana easterlies above. A simple model of wave ducting showed that the observed features were the evanescent extension of resonant waves ducted in the lower stable inversion layer. These are the first detailed observations, including vertical structure, of ducted waves associated with Santa Ana conditions. It is suggested that such waves should be a common feature in conditions occurring during Santa Ana events.
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Townshend, Ivan, Olu Awosoga, Judith Kulig, Anna Pujadas Botey, Blythe Shepard, and Bonita McFarlane. "Impacts of Wildfires on School Children: A Case Study of Slave Lake, Alberta, Canada." International Journal of Mass Emergencies & Disasters 33, no. 2 (2015): 148–87. http://dx.doi.org/10.1177/028072701503300202.
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Wildfires are becoming increasingly common, but there is limited understanding of their effects on children. This article reports on a study of wildfire impacts on children in a Canadian community. Self-reported measures of posttraumatic stress and coping and behavioral difficulties were obtained from a school-based survey of children in grades three to 12 carried out six months (T1) and 12 months (T2) after the fires. Students completed two screening instruments: the University of California at Los Angeles Post-traumatic Stress Disorder (PTSD) Reaction Index for Children and Adolescents – DSM-IV-TR, and the Strengths and Difficulties Questionnaire, and provided information about demographic details and loss of their home. Paired data (n = 140) revealed that a substantial number of children met certain PTSD criteria symptoms at T1 but the number declined by T2. Differences in symptoms by age, gender, and house loss were examined. Age and house loss were important differentiators of impact, but these waned through time, and house loss was not a defining trait of those most at risk of severe psychopathology. Future research examining children's responses to a variety of disasters would add to our knowledge about stress reactions while determining whether there are commonalities in responses across types of disasters.
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Apraku, C. Y., Y. A. Twumasi, Z. H. Ning, et al. "MAPPING FIRE SEVERITY FROM RECENT CALIFORNIA WILDFIRES USING SATELLITE IMAGERY." International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences XLVIII-M-3-2023 (September 5, 2023): 7–13. http://dx.doi.org/10.5194/isprs-archives-xlviii-m-3-2023-7-2023.
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Abstract. Urban sprawl has become a huge concern for cities like Los Angeles, New York, and Chicago in recent years. As urban sprawl pushes urbanization into city suburbs and outskirts, forest fragmentation becomes evidently prevalent and exposes forests to high temperatures, pollution, pests, and fires that threaten forest health. A 2021 report titled Rebuilding for a Resilient Recovery affirmed that the frequency and damage potential of wildfires have been exacerbated by climate change and urban sprawl especially in California. Globally, these fires can be attributed to both natural and anthropogenic drivers such as deforestation, agriculture, mining, and industrialization. Future projections predict that these incidences of fires will only worsen as the planet continues to warm further, with emphasis on the spread and intensities of the annual California wildfires over the decade. Quantifying the consequences of these fires on global climate change has become crucial and with the emergence of advanced GIS mapping tools, focus, visualization, and interpretation of fire and burn severity has become easier. However, knowledge and understanding of wildfire dynamics is limited especially in terms of fuel load, impacts on vegetation health, aerosol release and associated movement in the atmosphere. It is therefore important to address these gaps to make better and informed actions towards forest use, protection, management, and policies and broadly towards ambitious climate goals such as the UN’s Carbon Neutral goal by 2050. This study uses Sentinel 2A data from the Copernicus fleet between 2018 and 2022 to identify and assess the burn severity of affected areas in Sonoma County, California. The aim of the study is to understand the impacts of fires of fire on vegetation health and the post-fire recovery process. The Normalized Burn Ration Index (NBRI) was used to identify and measure the extent of the burnt areas within the county and their severity and Normalized Difference Vegetation Index (NDVI) was used as a measure of forest heath. The results show that Sonoma County has become a high burn severity area with a major decrease in unburned areas between 2018 and 2022. NDVI values recorded all decrease from January to December for all the years because of pre-fire season drought. The wildfire season begins in May and before then there are seasonal droughts that occur hence accounting for the initial decline in NDVI. The least values recorded were between 0.5 and 0.57 for September, indicating sparse and unhealthy vegetation because of sharp declines during the fire season.
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Benmarhnia, Tarik, Nicole A. Errett, and Joan A. Casey. "Beneath the smoke: Understanding the public health impacts of the Los Angeles urban wildfires." Environmental Epidemiology 9, no. 3 (2025): e388. https://doi.org/10.1097/ee9.0000000000000388.
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Borsdorff, Tobias, Josip Andrasec, Joost aan de Brugh, Haili Hu, Ilse Aben, and Jochen Landgraf. "Detection of carbon monoxide pollution from cities and wildfires on regional and urban scales: the benefit of CO column retrievals from SCIAMACHY 2.3 µm measurements under cloudy conditions." Atmospheric Measurement Techniques 11, no. 5 (2018): 2553–65. http://dx.doi.org/10.5194/amt-11-2553-2018.
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Abstract. In the perspective of the upcoming TROPOMI Sentinel-5 Precursor carbon monoxide data product, we discuss the benefit of using CO total column retrievals from cloud-contaminated SCIAMACHY 2.3 µm shortwave infrared spectra to detect atmospheric CO enhancements on regional and urban scales due to emissions from cities and wildfires. The study uses the operational Sentinel-5 Precursor algorithm SICOR, which infers the vertically integrated CO column together with effective cloud parameters. We investigate its capability to detect localized CO enhancements distinguishing between clear-sky observations and observations with low (< 1.5 km) and medium–high clouds (1.5–5 km). As an example, we analyse CO enhancements over the cities Paris, Los Angeles and Tehran as well as the wildfire events in Mexico–Guatemala 2005 and Alaska–Canada 2004. The CO average of the SCIAMACHY full-mission data set of clear-sky observations can detect weak CO enhancements of less than 10 ppb due to air pollution in these cities. For low-cloud conditions, the CO data product performs similarly well. For medium–high clouds, the observations show a reduced CO signal both over Tehran and Los Angeles, while for Paris no significant CO enhancement can be detected. This indicates that information about the vertical distribution of CO can be obtained from the SCIAMACHY measurements. Moreover, for the Mexico–Guatemala fires, the low-cloud CO data captures a strong outflow of CO over the Gulf of Mexico and the Pacific Ocean and so provides complementary information to clear-sky retrievals, which can only be obtained over land. For both burning events, enhanced CO values are even detectable with medium–high-cloud retrievals, confirming a distinct vertical extension of the pollution. The larger number of additional measurements, and hence the better spatial coverage, significantly improve the detection of wildfire pollution using both the clear-sky and cloudy CO retrievals. Due to the improved instrument performance of the TROPOMI instrument with respect to its precursor SCIAMACHY, the upcoming Sentinel-5 Precursor CO data product will allow improved detection of CO emissions and their vertical extension over cities and fires, making new research applications possible.
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Ko, Joseph, Trevor Krasowsky, and George Ban-Weiss. "Measurements to determine the mixing state of black carbon emitted from the 2017–2018 California wildfires and urban Los Angeles." Atmospheric Chemistry and Physics 20, no. 24 (2020): 15635–64. http://dx.doi.org/10.5194/acp-20-15635-2020.
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Abstract. The effects of atmospheric black carbon (BC) on climate and public health have been well established, but large uncertainties remain regarding the extent of the impacts of BC at different temporal and spatial scales. These uncertainties are largely due to the heterogeneous nature of BC in terms of its spatiotemporal distribution, mixing state, and coating composition. Here, we seek to further understand the size and mixing state of BC emitted from various sources and aged over different timescales using field measurements in the Los Angeles region. We measured refractory black carbon (rBC) with a single-particle soot photometer (SP2) on Catalina Island, California (∼70 km southwest of downtown Los Angeles) during three different time periods. During the first campaign (September 2017), westerly winds were dominant and measured air masses were representative of well-aged background over the Pacific Ocean. In the second and third campaigns (December 2017 and November 2018, respectively), atypical Santa Ana wind conditions allowed us to measure biomass burning rBC (BCbb) from air masses dominated by large biomass burning events in California and fossil fuel rBC (BCff) from the Los Angeles Basin. We observed that the emissions source type heavily influenced both the size distribution of the rBC cores and the rBC mixing state. BCbb had thicker coatings and larger core diameters than BBff. We observed a mean coating thickness (CTBC) of ∼40–70 nm and a count mean diameter (CMD) of ∼120 nm for BCbb. For BCff, we observed a CTBC of ∼5–15 nm and a CMD of ∼100 nm. Our observations also provided evidence that aging led to an increased CTBC for both BCbb and BCff. Aging timescales < ∼1 d were insufficient to thickly coat freshly emitted BCff. However, CTBC for aged BCff within aged background plumes was ∼35 nm thicker than CTBC for fresh BCff. Likewise, we found that CTBC for aged BCbb was ∼18 nm thicker than CTBC for fresh BCbb. The results presented in this study highlight the wide variability in the BC mixing state and provide additional evidence that the emissions source type and aging influence rBC microphysical properties.
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Muthukumar, Pratyush, Kabir Nagrecha, Dawn Comer, et al. "PM2.5 Air Pollution Prediction through Deep Learning Using Multisource Meteorological, Wildfire, and Heat Data." Atmosphere 13, no. 5 (2022): 822. http://dx.doi.org/10.3390/atmos13050822.
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Air pollution is a lethal global threat. To mitigate the effects of air pollution, we must first understand it, find its patterns and correlations, and predict it in advance. Air pollution is highly dependent on spatial and temporal correlations of prior meteorological, wildfire, and pollution structures. We use the advanced deep predictive Convolutional LSTM (ConvLSTM) model paired with the cutting-edge Graph Convolutional Network (GCN) architecture to predict spatiotemporal hourly PM2.5 across the Los Angeles area over time. Our deep-learning model does not use atmospheric physics or chemical mechanism data, but rather multisource imagery and sensor data. We use high-resolution remote-sensing satellite imagery from the Moderate Resolution Imaging Spectroradiometer (MODIS) instrument onboard the NASA Terra+Aqua satellites and remote-sensing data from the Tropospheric Monitoring Instrument (TROPOMI), a multispectral imaging spectrometer onboard the Sentinel-5P satellite. We use the highly correlated Fire Radiative Power data product from the MODIS instrument which provides valuable information about the radiant heat output and effects of wildfires on atmospheric air pollutants. The input data we use in our deep-learning model is representative of the major sources of ground-level PM2.5 and thus we can predict hourly PM2.5 at unparalleled accuracies. Our RMSE and NRMSE scores over various site locations and predictive time frames show significant improvement over existing research in predicting PM2.5 using spatiotemporal deep predictive algorithms.
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Kajita, Emily, Karen Chang, Vannalyn de Leon, et al. "Notes from the Field: Emergency Department Use During the Los Angeles County Wildfires, January 2025." MMWR. Morbidity and Mortality Weekly Report 74, no. 3 (2025): 40–42. https://doi.org/10.15585/mmwr.mm7403a2.
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Verma, Vishal, Andrea Polidori, James J. Schauer, Martin M. Shafer, Flemming R. Cassee, and Constantinos Sioutas. "Physicochemical and Toxicological Profiles of Particulate Matter in Los Angeles during the October 2007 Southern California Wildfires." Environmental Science & Technology 43, no. 3 (2009): 954–60. http://dx.doi.org/10.1021/es8021667.
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Dennison, Philip E., and Max A. Moritz. "Critical live fuel moisture in chaparral ecosystems: a threshold for fire activity and its relationship to antecedent precipitation." International Journal of Wildland Fire 18, no. 8 (2009): 1021. http://dx.doi.org/10.1071/wf08055.
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Large wildfires in southern California typically occur during periods of reduced live fuel moisture (LFM) and high winds. Previous work has found evidence that a LFM threshold may determine when large fires can occur. Using a LFM time series and a fire history for Los Angeles County, California, we found strong evidence for a LFM threshold near 79%. Monthly and 3-month total precipitation data were used to show that the timing of this threshold during the fire season is strongly correlated with antecedent rainfall. Spring precipitation, particularly in the month of March, was found to be the primary driver of the timing of LFM decline, although regression tree analysis revealed that high winter precipitation may delay the timing of the threshold in some years. This work further establishes relationships between precipitation and fire potential that may prove important for anticipating shifts in fire regimes under climate-change scenarios.
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Dwi Savandha, Septien, Amelia Amelia, and Ginna Novarianti Dwi Putri Pramesti. "From Headlines to Public Awareness: A Media Discourse Analysis of The Los Angeles 2025 Wildfire." WINTER JOURNAL: IMWI STUDENT RESEARCH JOURNAL 6, no. 1 (2025): 43–54. https://doi.org/10.52851/wt.v6i1.67.
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The 2025 Los Angeles wildfires reflect the serious challenges of disaster management in the era of climate change. Increasing extreme temperatures and droughts have exacerbated the frequency and intensity of fires, resulting in significant damage to the environment, public health, and local economies. This study aims to evaluate the effectiveness of firefighting resources and identify community responses to the disaster. The methods used are content analysis of news from mass media and observation of community responses through social media. Samples were taken purposively from relevant news and posts during the fire incident. The results showed that more than 8,500 firefighters were deployed, utilizing somewhat effective air and ground extinguishing strategies, which increased fire control from 14% to 24% within a few days. On the other hand, 205,000 residents were successfully evacuated, indicating a high level of public awareness and preparedness. Approximately 65% of residents were also actively involved in fire prevention efforts, with social media serving as the primary means of disseminating information. In conclusion, the success of fire control is greatly influenced by resource coordination and community participation. This research makes a significant contribution to the development of more responsive and collaborative fire mitigation strategies in the future, particularly in the context of growing risks associated with climate change.
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Wonaschütz, A., S. P. Hersey, A. Sorooshian, et al. "Impact of a large wildfire on water-soluble organic aerosol in a major urban area: the 2009 Station Fire in Los Angeles County." Atmospheric Chemistry and Physics 11, no. 16 (2011): 8257–70. http://dx.doi.org/10.5194/acp-11-8257-2011.
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Abstract. This study examines the nature of water-soluble organic aerosol measured in Pasadena, CA, under typical conditions and under the influence of a large wildfire (the 2009 Station Fire). During non-fire periods, water-soluble organic carbon (WSOC) variability was driven by photochemical production processes and sea breeze transport, resulting in an average diurnal cycle with a maximum at 15:00 local time (up to 4.9 μg C m−3). During the Station Fire, primary production was a key formation mechanism for WSOC. High concentrations of WSOC (up to 41 μg C m−3) in smoke plumes advected to the site in the morning hours were tightly correlated with nitrate and chloride, numerous aerosol mass spectrometer (AMS) organic mass spectral markers, and total non-refractory organic mass. Processed residual smoke was transported to the measurement site by the sea breeze later in the day, leading to higher afternoon WSOC levels than on non-fire days. Parameters representing higher degrees of oxidation of organics, including the ratios of the organic metrics m/z 44:m/z 57 and m/z 44:m/z 43, were elevated in those air masses. Intercomparisons of relative amounts of WSOC, organics, m/z 44, and m/z 43 show that the fraction of WSOC comprising acid-oxygenates increased as a function of photochemical aging owing to the conversion of aliphatic and non-acid oxygenated organics to more acid-like organics. The contribution of water-soluble organic species to the organic mass budget (10th–90th percentile values) ranged between 27 %–72 % and 27 %–68 % during fire and non-fire periods, respectively. The seasonal incidence of wildfires in the Los Angeles Basin greatly enhances the importance of water-soluble organics, which has implications for the radiative and hygroscopic properties of the regional aerosol.
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Parrish, David D., Ian C. Faloona, and Richard G. Derwent. "Maximum ozone concentrations in the southwestern US and Texas: implications of the growing predominance of the background contribution." Atmospheric Chemistry and Physics 25, no. 1 (2025): 263–89. https://doi.org/10.5194/acp-25-263-2025.
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Abstract. We utilize a simple, observation-based model to quantitatively estimate the US anthropogenic, background and wildfire contributions to the temporal and spatial distributions of maximum ozone concentrations throughout the southwestern US, including Texas and parts of California. The very different temporal variations in the separate contributions provide the basis for this analysis: over the past 4 decades the anthropogenic contribution has decreased at an approximately exponential rate by a factor of ∼ 6.3, while the US background concentration rose significantly through the 1980s and 1990s, reached a maximum in the mid-2000s, and has since slowly decreased. We primarily analyze ozone design values (ODVs), the statistic upon which the US National Ambient Air Quality Standards (NAAQS) are based. The ODV is an extreme value statistic that quantifies the relatively rare maximum observed ozone concentrations; thus, ODV time series provide spatially and temporally resolved records of maximum ozone concentrations throughout the country. Recent contributions of US background ozone to ODVs (primarily due to transported baseline ozone) are 64–70 ppb (parts per billion) over most of the southwestern US, and wildfires (also generally considered a background contribution) add further enhancements of 2–6 ppb in southwestern US urban areas. US anthropogenic emissions from urban and industrial sectors now produce only relatively modest enhancements to ODVs (less than ∼ 6 ppb in 2020) outside of the three largest urban areas considered (Dallas, Houston and Los Angeles), where the 2020 enhancements were in the 17–30 ppb range. As a consequence, US background ozone concentrations now dominate over US anthropogenic contributions in the western US, including the Los Angeles urban basin, where the largest US ozone concentrations are observed. In the southwestern US, this predominance is so pronounced that the US background plus wildfire contributions to ODVs approach or exceed the US NAAQS threshold for ozone of 70 ppb (implemented in 2015) and 75 ppb (implemented in 2008); consequently, NAAQS achievement has been precluded in this region. The large background contribution in this region has led to a pronounced shift in the spatial distribution of maximum US ozone concentrations; once ubiquitous nearly nationwide, ODVs of 75 ppb or greater have nearly disappeared in the eastern US, but such values are still frequent in the southwestern US. By 2021, the trend in maximum ODVs in two of the more highly populated eastern urban areas (i.e., New York City and Atlanta) had decreased to the point that they were smaller than those in significantly less populated southwestern US urban areas and nearly as small as ODVs recorded at isolated rural southwestern US sites. Two implications arise from these findings. First, alternate emission control strategies may provide more effective approaches to ozone air quality improvement; as background ozone makes the dominant contribution to even the highest observed concentrations, an international effort to reduce northern midlatitude baseline ozone concentrations could be pursued, or a standard based on the anthropogenic increment above the regionally varying US background ozone concentration could be considered to provide a regionally uniform emission reduction challenge. Second, the predominant contribution of US background ozone across the southwestern US presents a profound challenge for air quality modeling, as a manifold of stratospheric and tropospheric processes occurring at small spatial scales but over hemisphere-wide distances must be accurately treated in detail to predict present and future background contributions to daily maximum ozone concentrations at local scales.
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Venecek, Melissa A., Xin Yu, and Michael J. Kleeman. "Predicted ultrafine particulate matter source contribution across the continental United States during summertime air pollution events." Atmospheric Chemistry and Physics 19, no. 14 (2019): 9399–412. http://dx.doi.org/10.5194/acp-19-9399-2019.
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Abstract. The regional concentrations of airborne ultrafine particulate matter mass (Dp<0.1 µm; PM0.1) were predicted in 39 cities across the United States (US) during summertime air pollution episodes. Calculations were performed using a regional source-oriented chemical transport model with 4 km spatial resolution operating on the National Emissions Inventory created by the U.S. Environmental Protection Agency (EPA). Measured source profiles for particle size and composition between 0.01 and 10 µm were used to translate PM total mass to PM0.1. Predicted PM0.1 concentrations exceeded 2 µg m−3 during summer pollution episodes in major urban regions across the US including Los Angeles, the San Francisco Bay Area, Houston, Miami, and New York. PM0.1 spatial gradients were sharper than PM2.5 spatial gradients due to the dominance of primary aerosol in PM0.1. Artificial source tags were used to track contributions to primary PM0.1 and PM2.5 from 15 source categories. On-road gasoline and diesel vehicles made significant contributions to regional PM0.1 in all 39 cities even though peak contributions within 0.3 km of the roadway were not resolved by the 4 km grid cells. Cooking also made significant contributions to PM0.1 in all cities but biomass combustion was only important in locations impacted by summer wildfires. Aviation was a significant source of PM0.1 in cities that had airports within their urban footprints. Industrial sources, including cement manufacturing, process heating, steel foundries, and paper and pulp processing, impacted their immediate vicinity but did not significantly contribute to PM0.1 concentrations in any of the target 39 cities. Natural gas combustion made significant contributions to PM0.1 concentrations due to the widespread use of this fuel for electricity generation, industrial applications, residential use, and commercial use. The major sources of primary PM0.1 and PM2.5 were notably different in many cities. Future epidemiological studies may be able to differentiate PM0.1 and PM2.5 health effects by contrasting cities with different ratios of PM0.1∕PM2.5. In the current study, cities with higher PM0.1∕PM2.5 ratios (ratio greater than 0.10) include Houston, TX, Los Angeles, CA, Bakersfield, CA, Salt Lake City, UT, and Cleveland, OH. Cities with lower PM0.1 to PM2.5 ratios (ratio lower than 0.05) include Lake Charles, LA, Baton Rouge, LA, St. Louis, MO, Baltimore, MD, and Washington, D.C.
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Kant Awasthi, Rajani. "Direct Disaster Losses: A Case Study of Los Angeles and California Wildfire." International Journal of Science and Research (IJSR) 14, no. 1 (2025): 666–70. https://doi.org/10.21275/sr25115144046.
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Xu, Haiyong, and Frederic Paik Schoenberg. "Point process modeling of wildfire hazard in Los Angeles County, California." Annals of Applied Statistics 5, no. 2A (2011): 684–704. http://dx.doi.org/10.1214/10-aoas401.
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Palinkas, Lawrence A., Jessenia De Leon, Kexin Yu, et al. "Adaptation Resources and Responses to Wildfire Smoke and Other Forms of Air Pollution in Low-Income Urban Settings: A Mixed-Methods Study." International Journal of Environmental Research and Public Health 20, no. 7 (2023): 5393. http://dx.doi.org/10.3390/ijerph20075393.
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Little is known about how low-income residents of urban communities engage their knowledge, attitudes, behaviors, and resources to mitigate the health impacts of wildfire smoke and other forms of air pollution. We interviewed 40 adults in Los Angeles, California, to explore their threat assessments of days of poor air quality, adaptation resources and behaviors, and the impacts of air pollution and wildfire smoke on physical and mental health. Participants resided in census tracts that were disproportionately burdened by air pollution and socioeconomic vulnerability. All participants reported experiencing days of poor air quality due primarily to wildfire smoke. Sixty percent received advanced warnings of days of poor air quality or routinely monitored air quality via cell phone apps or news broadcasts. Adaptation behaviors included remaining indoors, circulating indoor air, and wearing face masks when outdoors. Most (82.5%) of the participants reported some physical or mental health problem or symptom during days of poor air quality, but several indicated that symptom severity was mitigated by their adaptive behaviors. Although low-income residents perceive themselves to be at risk for the physical and mental health impacts of air pollution, they have also adapted to that risk with limited resources.
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Deen, Sophia, Tatiana Kuzmenko, Hossein Asghari, and Demian A. Willette. "Investigating Los Angeles’ urban roadway network from a biologically-formed perspective." PeerJ 8 (January 13, 2020): e8238. http://dx.doi.org/10.7717/peerj.8238.
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The evolution of networks is constrained by spatial properties of the environment; a characterization that is true in both biological and built networks. Hence built networks such as urban streets can be compared to biological networks to reveal differences in efficiency and complexity. This study assessed foraging networks created by the slime-mold Physarium polycephalum on proportional 3D-printed topographic maps of metropolitan city of Los Angeles, California. Rapidly-generated isomorphic solutions were found to be consistently and statistically shorter than existing roadways in system length. Slime mold also allocated resources to supporting key nodes, analogous to how heavy traffic flows through major intersections. Further, chemical deterrents inhibited exploration of slime mold in selected areas and allows for testing of network redundancy and system resilience, such as after an earthquake or wildfire.
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Squire, Benjamin, Cathy Chidester, and Stephanie Raby. "Medical Events During the 2009 Los Angeles County Station Fire: Lessons for Wildfire EMS Planning." Prehospital Emergency Care 15, no. 4 (2011): 464–72. http://dx.doi.org/10.3109/10903127.2011.598607.
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Rolinski, Tom, Scott B. Capps, Robert G. Fovell, Yang Cao, Brian J. D’Agostino, and Steve Vanderburg. "The Santa Ana Wildfire Threat Index: Methodology and Operational Implementation." Weather and Forecasting 31, no. 6 (2016): 1881–97. http://dx.doi.org/10.1175/waf-d-15-0141.1.
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Abstract Santa Ana winds, common to Southern California from the fall through early spring, are a type of downslope windstorm originating from a direction generally ranging from 360°/0° to 100° and are usually accompanied by very low humidity. Since fuel conditions tend to be driest from late September through the middle of November, Santa Ana winds occurring during this time have the greatest potential to produce large, devastating fires upon ignition. Such catastrophic fires occurred in 1993, 2003, 2007, and 2008. Because of the destructive nature of such fires, there has been a growing desire to categorize Santa Ana wind events in much the same way that tropical cyclones have been categorized. The Santa Ana wildfire threat index (SAWTI) is a tool for categorizing Santa Ana wind events with respect to anticipated fire potential. The latest version of the index has been a result of a three-and-a-half-year collaboration effort between the USDA Forest Service, the San Diego Gas and Electric utility (SDG&E), and the University of California, Los Angeles (UCLA). The SAWTI uses several meteorological and fuel moisture variables at 3-km resolution as input to the Weather Research and Forecasting (WRF) Model to generate the index out to 6 days. In addition to the index, a 30-yr climatology of weather, fuels, and the SAWTI has been developed to help put current and future events into perspective. This paper outlines the methodology for developing the SAWTI, including a discussion on the various datasets employed and its operational implementation.
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Schoenberg, Frederic Paik, Jamie Pompa, and Chien-Hsun Chang. "A note on non-parametric and semi-parametric modeling of wildfire hazard in Los Angeles County, California." Environmental and Ecological Statistics 16, no. 2 (2008): 251–69. http://dx.doi.org/10.1007/s10651-007-0087-z.
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Burkett, Brice, and Andrew Curtis. "Classifying Wildfire Risk at the Building Scale in the Wildland-Urban Interface: Applying Spatial Video Approaches to Los Angeles County." Risk, Hazards & Crisis in Public Policy 2, no. 4 (2011): 1–20. http://dx.doi.org/10.2202/1944-4079.1093.
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Wonaschütz, A., S. P. Hersey, A. Sorooshian, et al. "Impact of a large wildfire on water-soluble organic aerosol in a major urban area: the 2009 Station Fire in Los Angeles County." Atmospheric Chemistry and Physics Discussions 11, no. 4 (2011): 12849–87. http://dx.doi.org/10.5194/acpd-11-12849-2011.
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Abstract. Water-soluble organic carbon is a major component of aerosol particles globally. This study examines a field dataset of water-soluble organic aerosol in the Los Angeles Basin, a classic urban setting, under typical conditions and under the influence of a large wildfire (the 2009 Station Fire). The measurements took place between July and September in Pasadena as part of the 2009 Pasadena Aerosol Characterization Observatory (PACO) field campaign. Large differences in the nature of water-soluble organic carbon (WSOC) were observed between periods with and without the influence of the fire. During non-fire periods, WSOC variability was driven most likely by a combination of photochemical production processes and subsequent sea breeze transport, resulting in an average diurnal cycle with a maximum at 15:00 LT (up to 4.9 μg C m−3). During the Station Fire, smoke plumes advected to the site in the morning hours were characterized by high concentrations of WSOC (up to 41 μg C m−3) in tight correlation with nitrate and chloride, and with Aerodyne Aerosol Mass Spectrometer (AMS) organic metrics such as the biomass burning tracer m/z 60, and total non-refractory organic mass. These concentrations and correlations and the proximity of the measurement site to the fire suggest that primary production was a key formation mechanism for WSOC. During the afternoons, the sea breeze transported urban pollution and processed residual smoke back to the measurement site, leading to higher afternoon WSOC levels than on non-fire days. Parameters representing higher degrees of oxidation of organics, including the ratios m/z 44 : m/z 57 and m/z 44 : m/z 43, were increased in those air masses. Intercomparisons of relative amounts of WSOC, AMS organic, m/z 44, and m/z 43 are used to examine how the relative abundance of different classes of WSOC species changed as a result of photochemical aging. The fraction of WSOC comprised of acid-oxygenates increased as a of photochemical aging owing to the conversion of aliphatic and non-acid oxygenated organics to more acid-like organics. Assuming a factor of 1.8 to convert WSOC concentrations to organic mass-equivalent concentrations, the contribution of water-soluble organic species to the organic mass budget (10th–90th percentile values) ranged between 27–72% and 27–68% during fire and non-fire periods, respectively. Therefore, WSOC is a significant contributor to the organic aerosol budget in this urban area. The influence of fires in this basin greatly enhances the importance of this class of organics, which has implications for the radiative and hygroscopic properties of the regional aerosol.
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Schrader-Patton, Charlie C., and Emma C. Underwood. "New Biomass Estimates for Chaparral-Dominated Southern California Landscapes." Remote Sensing 13, no. 8 (2021): 1581. http://dx.doi.org/10.3390/rs13081581.
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Chaparral shrublands are the dominant wildland vegetation type in Southern California and the most extensive ecosystem in the state. Disturbance by wildfire and climate change have created a dynamic landscape in which biomass mapping is key in tracking the ability of chaparral shrublands to sequester carbon. Despite this importance, most national and regional scale estimates do not account for shrubland biomass. Employing plot data from several sources, we built a random forest model to predict aboveground live biomass in Southern California using remote sensing data (Landsat Normalized Difference Vegetation Index (NDVI)) and a suite of geophysical variables. By substituting the NDVI and precipitation predictors for any given year, we were able to apply the model to each year from 2000 to 2019. Using a total of 980 field plots, our model had a k-fold cross-validation R2 of 0.51 and an RMSE of 3.9. Validation by vegetation type ranged from R2 = 0.17 (RMSE = 9.7) for Sierran mixed-conifer to R2 = 0.91 (RMSE = 2.3) for sagebrush. Our estimates showed an improvement in accuracy over two other biomass estimates that included shrublands, with an R2 = 0.82 (RMSE = 4.7) compared to R2 = 0.068 (RMSE = 6.7) for a global biomass estimate and R2 = 0.29 (RMSE = 5.9) for a regional biomass estimate. Given the importance of accurate biomass estimates for resource managers, we calculated the mean year 2010 shrubland biomasses for the four national forests that ranged from 3.5 kg/m2 (Los Padres) to 2.3 kg/m2 (Angeles and Cleveland). Finally, we compared our estimates to field-measured biomasses from the literature summarized by shrubland vegetation type and age class. Our model provides a transparent and repeatable method to generate biomass measurements in any year, thereby providing data to track biomass recovery after management actions or disturbances such as fire.
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Jorgensen, David P., Maiana N. Hanshaw, Kevin M. Schmidt, et al. "Value of a Dual-Polarized Gap-Filling Radar in Support of Southern California Post-Fire Debris-Flow Warnings." Journal of Hydrometeorology 12, no. 6 (2011): 1581–95. http://dx.doi.org/10.1175/jhm-d-11-05.1.
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Abstract A portable truck-mounted C-band Doppler weather radar was deployed to observe rainfall over the Station Fire burn area near Los Angeles, California, during the winter of 2009/10 to assist with debris-flow warning decisions. The deployments were a component of a joint NOAA–U.S. Geological Survey (USGS) research effort to improve definition of the rainfall conditions that trigger debris flows from steep topography within recent wildfire burn areas. A procedure was implemented to blend various dual-polarized estimators of precipitation (for radar observations taken below the freezing level) using threshold values for differential reflectivity and specific differential phase shift that improves the accuracy of the rainfall estimates over a specific burn area sited with terrestrial tipping-bucket rain gauges. The portable radar outperformed local Weather Surveillance Radar-1988 Doppler (WSR-88D) National Weather Service network radars in detecting rainfall capable of initiating post-fire runoff-generated debris flows. The network radars underestimated hourly precipitation totals by about 50%. Consistent with intensity–duration threshold curves determined from past debris-flow events in burned areas in Southern California, the portable radar-derived rainfall rates exceeded the empirical thresholds over a wider range of storm durations with a higher spatial resolution than local National Weather Service operational radars. Moreover, the truck-mounted C-band radar dual-polarimetric-derived estimates of rainfall intensity provided a better guide to the expected severity of debris-flow events, based on criteria derived from previous events using rain gauge data, than traditional radar-derived rainfall approaches using reflectivity–rainfall relationships for either the portable or operational network WSR-88D radars. Part of the reason for the improvement was due to siting the radar closer to the burn zone than the WSR-88Ds, but use of the dual-polarimetric variables improved the rainfall estimation by ~12% over the use of traditional Z–R relationships.
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Campbell, Michael J., Wesley G. Page, Philip E. Dennison, and Bret W. Butler. "Escape Route Index: A Spatially-Explicit Measure of Wildland Firefighter Egress Capacity." Fire 2, no. 3 (2019): 40. http://dx.doi.org/10.3390/fire2030040.
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For wildland firefighters, the ability to efficiently evacuate the fireline is limited by terrain, vegetation, and fire conditions. The impacts of terrain and vegetation on evacuation time to a safety zone may not be apparent when considering potential control locations either at the time of a wildfire or during pre-suppression planning. To address the need for a spatially-explicit measure of egress capacity, this paper introduces the Escape Route Index (ERI). Ranging from 0 to 1, ERI is a normalized ratio of the distance traveled within a time frame, accounting for impedance by slope and vegetation, to the optimal distance traveled in the absence of these impediments. An ERI approaching 1 indicates that terrain and vegetation conditions should have little impact on firefighter mobility while an ERI approaching 0 is representative of limited cross-country travel mobility. The directional nature of evacuation allows for the computation of four ERI metrics: (1) ERImean (average ERI in all travel directions); (2) ERImin (ERI in direction of lowest egress); (3) ERImax (ERI in direction of highest egress); and (4) ERIazimuth (azimuth of ERImax direction). We demonstrate the implementation of ERI for three different evacuation time frames (10, 20, and 30 min) on the Angeles National Forest in California, USA. A previously published, crowd-sourced relationship between slope and travel rate was used to account for terrain, while vegetation was accounted for by using land cover to adjust travel rates based on factors from the Wildland Fire Decision Support System (WFDSS). Land cover was found to have a stronger impact on ERI values than slope. We also modeled ERI values for several recent wildland firefighter entrapments to assess the degree to which landscape conditions may have contributed to these events, finding that ERI values were generally low from the crews’ evacuation starting points. We conclude that mapping ERI prior to engaging a fire could help inform overall firefighter risk for a given location and aid in identifying locations with greater egress capacity in which to focus wildland fire suppression, thus potentially reducing risk of entrapment. Continued improvements in accuracy of vegetation density mapping and increased availability of light detection and ranging (lidar) will greatly benefit future implementations of ERI.
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Hamilton, Sofia D., Dien Wu, Matthew S. Johnson, et al. "Estimating Carbon Dioxide Emissions in Two California Cities Using Bayesian Inversion and Satellite Measurements." Geophysical Research Letters 51, no. 20 (2024). http://dx.doi.org/10.1029/2024gl111150.
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AbstractNASA's Orbiting Carbon Observatories (OCO‐2 and OCO‐3) provide measurements of column‐averaged carbon dioxide concentrations (XCO2) with sufficient spatial resolution and precision to constrain bottom‐up estimates of CO2 fluxes at regional scales. We use Bayesian inversion methods assimilating satellite retrievals to improve estimates of CO2 fluxes in the South Coast Air Basin (SoCAB) which surrounds Los Angeles, and in the San Francisco Bay Area Air Basin (SFBA). We study 2020 to understand the impact of the COVID‐19 lockdowns and an active wildfire season. Our results indicated that a 50% (30%) reduction in CO2 emissions relative to 2015 during the COVID‐19 lockdown period was consistent with OCO measurements for SFBA (SoCAB). We find that posterior wildfire emissions differed significantly from the prior at the scale of individual wildfires, though with large uncertainties, and that wildfire emissions in SFBA are significant, attributing 72% of the region's CO2 emissions during August 2020 to wildfires.
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Kilkenny, Katherine, William Frishman, and Joseph S. Alpert. "Los Angeles Wildfires: Getting to the Heart of It." American Journal of Medicine, March 2025. https://doi.org/10.1016/j.amjmed.2025.02.028.
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"Wildfires Spare Los Angeles Area Cancer Centers—For Now." Cancer Discovery, 2025. https://doi.org/10.1158/2159-8290.cd-nw2025-0005.
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Goh, Ying-Ying, and Y. Tony Yang. "Wildfires and health: building resilience in Los Angeles’ climate crisis." Lancet, January 2025. https://doi.org/10.1016/s0140-6736(25)00129-1.
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Dieckman, Emily. "How Much Did Climate Change Affect the Los Angeles Wildfires?" Eos 106 (January 28, 2025). https://doi.org/10.1029/2025eo250042.
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Laughner, Joshua L., Jessica L. Neu, David Schimel, et al. "Societal shifts due to COVID-19 reveal large-scale complexities and feedbacks between atmospheric chemistry and climate change." Proceedings of the National Academy of Sciences 118, no. 46 (2021). http://dx.doi.org/10.1073/pnas.2109481118.
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Significance The COVID-19 pandemic and associated lockdowns caused significant changes to human activity that temporarily altered our imprint on the atmosphere, providing a brief glimpse of potential future changes in atmospheric composition. This event demonstrated key feedbacks within and between air quality and the carbon cycle: Improvements in air quality increased the lifetime of methane (an important greenhouse gas), while unusually hot weather and intense wildfires in Los Angeles drove poor air quality. This shows that efforts to reduce greenhouse gas emissions and improve air quality cannot be considered separately.
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Walker, Steven M., and Melody Ramos-Rea. "Leading Through Turbulence: A 40-Year Empirical Synthesis of Crisis Leadership." Journal of Leadership, Accountability and Ethics 22, no. 1 (2025). https://doi.org/10.33423/jlae.v22i1.7602.
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Over the past four decades, crises such as 9/11, Hurricane Katrina, the 2008 Great Recession, the COVID-19 pandemic, and the 2025 Los Angeles wildfires have exposed the strengths and shortcomings of leadership during unprecedented challenges. This article presents a thematic analysis of empirical peer-reviewed literature from 1985 to 2025, synthesizing lessons learned across diverse crises. By focusing on five core dimensions—decision-making under uncertainty, emotional intelligence, communication strategies, resilience-building, and ethical leadership—this analysis provides actionable insights for leaders navigating volatile, uncertain, complex, and ambiguous (VUCA) environments. The findings emphasize adaptability, transparency, empathy, and ethical stewardship as key factors that distinguish successful crisis leaders. The article also proposes a "Crisis Leadership Framework" to guide future leaders in addressing the dynamic demands of a rapidly changing world. Through this synthesis of research and practice, this article bridges academic insights with pragmatic tools, equipping leaders to respond effectively to global disruptions while fostering long-term resilience.
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McArthur, Sarah. "OUR FUTURE HINGES ON THE LEADERS WE FOLLOW." Leader to Leader, February 16, 2025. https://doi.org/10.1002/ltl.20889.
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AbstractThe author, Leader to Leader’s editor‐in‐chief, reflects on the devastating wildfires in the Los Angeles, California area and broadens this into a discussion on what it means to be a leader and a follower in today’s digital age. She notes that there are many definitions of the word leader, and that at the “most basic level,” there is a definition from a 1996 essay by Peter Drucker, which includes these words: “The only definition of a leader is someone who has followers. Some people are thinkers. Some are prophets. Both roles are important and badly needed. But without followers, there can be no leaders.” Yet, she notes that in today’s social media‐based culture, the word “followers” has taken on an additional meaning, with many millions of “followers” for athletes, actors, and other “influencers.” She further relates that “it is important to note that according to Drucker’s definition, these Instagram celebrities are in fact leaders in this relatively new era we call the Digital Age.” And that leaders’ “exceptional performance is rooted in their motivation to develop those around them and their focus is less about creating and enlisting more followers and more about creating more leaders for our organizations, our communities, and our countries of tomorrow.”
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McHale, Thomas C., David R. Boulware, Kelly Searle, et al. "P-1957. Spatiotemporal Association of COVID-19 Cases and Mortality with Exposure to Wildfire Particulate Matter in 2020." Open Forum Infectious Diseases 12, Supplement_1 (2025). https://doi.org/10.1093/ofid/ofae631.2116.
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Abstract Background Climate change is anticipated to have profound effects on human health including infectious diseases. Wildfires have increased in frequency and intensity due to changes in precipitation and have been linked to worsening respiratory infections. We aimed to demonstrate whether an association existed between wildfire smoke and COVID-19 in California during 2020. Demographic data by county in California based on the 2020 American Census Survey and New York Times mask-use survey conducted in July 2020. The population of California is generally higher in the southern region, especially Los Angeles County. The median income is highest in the San Francisco Bay area. The outdoor laborer rate is generally higher in northern California, especially the rural county of Trinity. Self-reported mask use in July 2020 was high throughout the state, but lowest in the northern region. Methods We performed a population-based ecologic cohort study in California in 2020 using a spatial autoregressive model to test for associations between wildfire smoke and COVID-19 case and death incidence while adjusting for demographic and environmental factors. The counties of California were the units of analysis and all persons who lived in California were accounted for in the data. We used publicly available levels of particulate matter &lt; 2.5 µm (µg/m3 PM2.5) specifically attributable to wildfire smoke in California during 2020. The median COVID-19 case and death incidence for each county in California and the overall case and death incidence in each county in California and the statewide county median case and death incidence is displayed in the first two plots below. The mean wildfire smoke PM2.5 exposure (µg/m3) in each California county and the median smoke exposure among California counties is displayed in the third plot. There was a surge in COVID-19 cases and deaths in California in the summer and winter of 2020 but a large degree of variation across counties. There was a surge in smoke exposure in the fall of 2020 and a large degree of variation across counties. Results In a model adjusted for spatial autocorrelation, environmental and demographic confounders, we found as smoke exposure increased per each 10 µg/m3 in PM2.5, there was an average increase of 175 COVID-19 cases/10,000 persons the following month (1-month lag) at the county level (P&lt; 0.001) and an increase of 1.86 COVID-19 deaths/10,000 persons the following month at the county level (P&lt; 0.001). These findings were attenuated in the 2nd month after smoke exposure where we found as smoke increased per each 10 µg/m3 in PM2.5 there was an average increase of 65.9 COVID-19 cases/10,000 persons the following 2nd month but no increase in deaths. Screenshot of the interactive Shiny app displaying COVID-19 cases, deaths, and smoke PM2.5 for each county in California and each month of 2020. Link: https://mchal053.shinyapps.io/smoke-covid/. Conclusion 2020 was a particularly strong year for wildfires in California and a unique year for infectious diseases with the COVID-19 pandemic. Our findings, using a spatially adjusted autoregressive model which controlled for important confounding variables, demonstrated that wildfire smoke exposure likely increased COVID-19 acquisition potentially via epithelial injury. This may have implications for the transmission risk for other upper respiratory tract infections. Table 1 Adjusted spatial lag model for the COVID-19 case and death incidence per 10,000 persons per 10 µg/m3 increase in PM2.5 smoke exposure in 2020. The model is adjusted for median income, outdoor laborer rate, average 2020 temperature per county, monthly 2020 precipitation per county, average elevation, month of the year, and rate of respondents reporting “Always” wearing a mask when in public within 6-feet of other another person. We found very strong evidence for a 1-month lag increase of 175 COIVD-19 cases/10,000 persons and 1.86 deaths/10,000 persons and a 2-month lag increase of 65.9 COVID-19 cases/10,000 persons. There was no 2-month lag increase in COVID-19 mortality. Disclosures Andrej Spec, MD, MSCI, F2G: Grant/Research Support George R. Thompson, III, MD, Astellas: Advisor/Consultant|Cidara: Advisor/Consultant|Cidara: Grant/Research Support|F2G: Advisor/Consultant|F2G: Grant/Research Support|Melinta: Advisor/Consultant|Melinta: Grant/Research Support|Mundipharma: Advisor/Consultant|Mundipharma: Grant/Research Support|Pfizer: Advisor/Consultant
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An, Karen, Cathleen E. Jones, and Yunling Lou. "Assessment of Pre‐ and Post‐Fire Fuel Availability for Wildfire Management Based on L‐Band Polarimetric SAR." Earth and Space Science 11, no. 4 (2024). http://dx.doi.org/10.1029/2023ea002943.
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AbstractMany communities coexist with wildfires that lead to loss of lives, property, and ecosystem services. Remote sensing tools can aid disaster response and post‐event assessment, offering fire agencies opportunities for additional surveillance with radar, an all‐weather instrument that can image day or night. The Station (2009) and Bobcat (2020) Fires are the two largest fires in Los Angeles County history, each burning over 100,000 acres. These areas are imaged with NASA's Uninhabited Aerial Vehicle Synthetic Aperture Radar L‐band instrument. We test whether polarimetric radar can detect fire scars, burn severity, and different fuel types through its sensitivity to different scattering mechanisms. Polarimetric SAR products are moved into geographic information system‐friendly formats, and in lieu of available field measurements are analyzed alongside agency data showing fire perimeters, burn progression outlines, and soil burn severity. We find that the HV polarization returns and the primary scattering mechanism, quantified through the Cloude‐Pottier decomposition, are the most sensitive parameters. Higher HV values pre‐fire correspond well to areas of moderate and high soil burn severity, and the pattern of fire progression follows higher HV to some extent. Using an HV difference threshold of 1.5 dB, the Bobcat burn scar is identified at 0.70 accuracy when compared with the published fire perimeter. Alpha 1 Angle can also demonstrate sensitivity to soil burn severity pre‐ and post‐fire, showing vegetation types with increased surface scattering post‐fire, which can be used to map burn scars and track recovery by vegetation type.