Our Research

The following projects include active grants with open positions. For more information, please contact us.

Beyond wildfire fine particles and average effects, modelling wildfire-specific PM10 and Ozone and vulnerable subgroups using modern machine learning algorithms

Funding institution: CalEPA
PI: Tarik Benmarhnia

The aim of this project is to apply recent techniques based on machine learning algorithms to model wildfire specific PM10 and O3 and then identify subgroups of the population that are particularly vulnerable to such wildfires’ mixtures. Fires contribute to enhanced surface concentrations of various air pollutants. Fine particulate matter (PM2.5) is by far the most investigated air pollutant generated by wildfires in California and globally. However, wildfire can also contribute to the generation of other pollutants that are monitored and regulated including coarse PM (PM10) and tropospheric Ozone (O3). Recent studies have shown that wildfires generate increases in tropospheric O3 levels through processes distinct from PM2.5. The epidemiological evidence regarding acute exposure to PM10 and O3 is vast. Yet, very few studies have been aimed at quantifying the impacts of such pollutants in relation to wildfires emissions.  In this project, we will expand our recently developed approach to model wildfire specific PM10 and O3 with fine spatial and temporal resolutions that could be directly merged with health data such hospital admissions. We will also leverage modern mixtures methods based on quantile g-computation to study the synergetic impacts of these pollutants (PM2.5, PM10, O3) specifically attributable to wildfires. Furthermore, though the environmental justice literature has found that socioeconomic and racial and ethnic minorities suffer from a disproportionate burden of air pollution exposure in general, and PM2.5 in particular, studies assessing the extent to which certain socio-demographic characteristics modify the smoke pollution-health risk remain limited. We will adopt a data-driven approach based on recursive partitioning methods to comprehensively characterize heterogeneous effects and constitute susceptibility profiles regarding wildfire health impacts considering a large set of individual and neighborhood-level social and environmental characteristics. 

Extreme weather, air pollution, and stroke among an aging female population

Funding institution: National Institutes of Health
In collaboration with City of Hope

Wildfires adversely affect air quality through smoke and winds, and in California, the occurrence of and effects from these wildfires have been exacerbated by an extended drought. Despite environmental policies that have curtailed air pollution in the state, a number of metropolitan California counties have particulate pollution levels above federal and state ambient standards. During extreme weather events including heat waves and/or active wildfires, these levels rival that of the worst cities in the world. Aging populations are of particular concern during extreme weather events as air pollution can exacerbate underlying risk factors for cardiovascular diseases (CVD). The prevalence of both stroke and CVD risk factors also markedly increases with age, making older adults and, specifically, post-menopausal women particularly susceptible to environmental impacts. This study aims to uncover the intersection between air pollution and extreme weather events (wildfire, heat index) in the context of the underlying environment (drought, heat/temperature) and the fluidity of daily weather (wind), and simultaneously consider personal risk factors that contribute to one’s susceptibility to environmental stressors. In this project, we will: evaluate acute effects from wildfire events by ascertaining stroke events within geographically affected areas based on satellite imagery, evaluate the effects of drought and wildfire events on specific sources and components of air pollution and determine the role of specific PM2.5 components in stroke risk and mortality, and evaluate the association between PM2.5 and immune markers. 

Susceptibility and adverse health outcomes related to climate-sensitive events among older Medicare beneficiaries with Alzheimer and Dementia

Funding institution: National Institute on Aging
PI: Tarik Benmarhnia 

The burden of Alzheimer’s disease (AD) and related dementias (ADRD) is expected to double by 2060 with almost 14 million people affected. Simultaneously, air pollution remains a health burden, with >100 million persons in the US living in areas exceeding health-based regulations for fine particles and ozone. Exposure to wildfire smoke is also increasing. Many studies have reported that exposure to air pollution can increase the risk of AD/ADRD, suggesting that the environmental impact of climate change could, in fact, become a brain health emergency that we are unprepared to tackle. This work capitalizes on a large and validated cohort of US Medicare beneficiaries (>65y) with AD/ADRD (approx. 10 million beneficiaries for the period 2000-2019) and spatially resolved weather data combined with state-of-the-science machine learning for estimating exposure to air pollution including wildfire smoke, leveraging satellite imagery, land use data, and monitors. Our long-term goals are to characterize the vulnerability and health impacts of climate change-related exposures within a large cohort of older adults with AD/ADRD. Results from this work will advance evidence-based policies and action to protect older populations with AD/ADRD under several converging trends: the co-occurrence of multiple exposures of extreme weather and air pollution; the rapidly aging US population; increasing extreme weather events; increasing wildfires and subsequent smoke; and health inequities. 

Heat waves in the Southern California coastal zone: Their oceanic and atmospheric drivers, human health impacts, and sustainable adaptation

Funding institution: National Science Foundation
PI: Mark Merrifield
Project website

Extreme heat is the number one weather-related cause of death in the US, and its impacts are felt especially strongly in the diverse, densely populated coastal zone of Southern California, where heat exposure has been shown to dramatically affect population mortality and morbidity. Furthermore, spatial heterogeneity in the impacts of heat due to factors such as the urban heat-island effect, which disproportionately affects disadvantaged populations, has made this an issue of environmental justice. Equitable adaptation strategies are needed. One oft-suggested heat adaptation approach is urban greening. However, there is scant research addressing the climate suitability of and fresh water constraints on urban greening potential – a possible limiting factor that could make or break long-term greening efforts, especially in arid and drought-prone regions like Southern California. This research hub will address the issue of extreme heat amidst climate change, and sustainable and equitable long-term solutions to heat in Southern California’s coastal zone. We will answer critical convergent questions concerning: 1) the atmosphere-land-ocean dynamics that drive and modulate patterns of extreme heat; 2) localized health impacts of extreme heat, with an emphasis on how the built environment and socioeconomic factors determine who faces the brunt of heat-health impacts; and 3) regionally-specific vegetation-temperature relationships, and the climate suitability and water needs of urban greening efforts. Central to the Hub is the co-production of sustainable intervention strategies that consider climate dynamics, public health, and ecohydrological constraints along with the goals and needs of local communities. Informing this research at every step will be input from a collective of local and regional government agencies, NGOs, and community groups that are already invested and engaged in climate change adaptation.

Impacts of Multiple Climate Change Stressors on Health in California

Funding institution: California Air Resources Board
PIs: Miriam Marlier and Tarik Benmarhnia

Although often examined individually, populations in California are increasingly exposed to multiple climate stressors at the same place and time. This includes, for example, wildfires or air pollution co-occurring with extreme heat. Exposure to multiple climate stressors may exacerbate certain health conditions and disproportionately affect vulnerable populations, but there is a lack of a comprehensive evaluation of these effects. The overarching objective of this project is to understand the joint effect of multiple climate-related stressors and the heterogeneity across potentially vulnerable communities in different regions of California. In this project, the Contractor will produce a literature review of the individual and combined impact of multiple climate stressors on health outcomes with a focus in the United States (U.S.) and California. The Contractor (University of California, Los Angeles [UCLA]) will map regional variations in climate stressor exposure across California over the past fifteen years, with a particular focus on heat, air pollution, wildfires, and precipitation extremes, while also exploring the modulating effect of droughts. These exposures will be linked to multiple health outcomes to quantify health impacts and associated costs across the life course of different populations. The Contractor will also evaluate how social determinants of health and long-term patterns of climate stressors modify the health risks analyzed. This work will support the California Air Resources Board (CARB) in quantifying comprehensive health co-benefits potentially associated with actions to reduce California’s greenhouse gas emissions and identify pathways to protect vulnerable populations throughout the State.

Modulation of Climate Risks by Intensification of Urban and Agricultural Land Uses in the Arabian Peninsula

Funding institution: NASA
PI: Cascade Tuholske

Climate change is increasing the duration, frequency, and intensity of hot-humid heat waves across the world. Due to a combination of intense heating of inland desserts and proximity to warm Red Sea and Persian Gulf waters, the Arabian Peninsula contends with the world’s most extreme humid-heat conditions. The region has been warming nearly twice as fast as the global average, and peak values of humid heat are approaching the limits of human survivability. Concurrently, rapid growth in population and sovereign wealth has driven large-scale land-cover and land-use change (LCLUC) across the Arabian Peninsula in recent decades. Urbanization, ranging from high-rise buildings to suburban housing developments, and agricultural expansion and intensification have transformed stretches of the desert landscape. Much of this LCLUC is accompanied by the presence of socioeconomically vulnerable migrant laborers in the agriculture and construction sectors who face increasingly deadly heat stress. However, the fine-grained interactions between rapid LCLUC and extreme heat are not well understood for the Arabian Peninsula, much less the impacts to human health and wellbeing, despite continued warming having serious heat-stress implications for people living and working in the region. The absence of a holistic analysis of the physical and societal interactions between large-scale LCLUC and extreme heat limits stakeholders’ ability to target mitigative and adaptive actions to reduce LCLUC-related heat stress. This research will add to the NASA LCLUC program by developing a remote-sensing-enabled framework to help anticipate and manage climate risk in a region on the front lines of climate change, particularly through actionable evidence about the most exposed and vulnerable communities.

Accelerating Climate Emergency Response to Wildfire Smoke to Improve Health and Resilience

Funding institution: University of California Office of the President
PI: Harold Collard

Climate change is driving a wildfire crisis that is polluting California’s air. Wildfire smoke harms population health both near and far from fire risk areas and drives significant health disparities. While California is acting to address destructive wildfires, it has paid insufficient attention to the health threats from wildfire smoke. The contradicts the State’s Climate Adaptation Strategy, which sees wildfire smoke as an urgent public health risk that requires action. In alignment with California’s climate goals, we propose to improve public health and protect climate vulnerable communities from wildfire smoke, using the San Francisco Bay Area as a model. Specifically, the proposal outlines three objectives. First, we will use novel machine learning technologies to identify SF Bay Area populations most at risk of adverse health outcomes from wildfire smoke. Second, we will assess how strategies to mitigate the adverse health impacts of wildfire smoke are currently deployed by public health departments and community organizations in the SF Bay Area, and, importantly, whether they are effective. Finally, we will utilize what is learned to activate clinical and community emergency response to wildfire smoke events in the SF Bay Area.

California Community and Earth-system Integrated Climate Resilience Center (CalCEI CRC)

Funding institution: US Department of Energy
PI: Minghui Diao

The state of California is home to 39.2 million people and is one of the most ethnically diverse states in the US. California faces a multitude of threats from climate change, e.g., catastrophic wildfires, droughts, heat waves, storms, and flooding. An urgency thus exists to build a DOE Climate Resilience Center to examine, predict, and remediate climate change impacts on all communities in the region. Our overarching goal is to examine and predict interactions among climate change and multi-ethnic communities. This project will quantify how the disparity of various climate impacts (e.g., wildfires, heat waves, storms) will be exacerbated by a changing climate and build metrics to quantify the effectiveness and equity of various solutions. This will be achieved through integrating the field observations with an Earth-system model and other applied science models such as epidemiological models. We will build an integrated modeling framework to support decision makers with their adaptation and resilience planning. Our proposed work is driven by three key scientific questions, aiming to advance the basic sciences that improve the understanding, forecasting, and mitigation of climate change in California: Science Question 1: What are the added values of understanding the spatial heterogeneity of physical processes and key meteorological conditions (e.g., temperature, humidity, aerosols, gases and precipitation) at high resolution (3 km) for estimating climate impacts on communities in California? Science Question 2: What are the compounding effects of wildfire smoke emissions and extreme heat on public health in the Bay Area in the past five years through selective case studies? Science Question 3: How can we build a modeling framework that can translate resilience plans into quantifiable metrics such as public health impacts? What are the health benefits of possible mitigation and adaptation plans (e.g., air conditioning and green spaces) in various communities in the next 50 years?