Current and Recent Research on Air Pollution

EHSC members are currently working on several research projects focusing on different aspects of air pollution in California. Among these projects are:

Toxic air pollutants in California environmental justice communities

Principal Investigators: Clare Cannon and Anthony Wexler
Funded by UC Multiprograms Research and Initiatives

In 2017, California enacted Assembly Bill 617 (AB617): “The Community Air Protection Program.” AB617 established the nation’s first state-run community-scale program to detect air pollution hotspots, helping to reduce air pollutants that tend to occur at higher levels in low-income communities of color. The development of new air pollution measurement tools to implement AB617 can be an exceptional form of relief for these communities who for years have been advocating for access to cleaner air. Disadvantaged communities in California are typically exposed to two kinds of hazardous air pollutants (HAPs): toxic metals and toxic volatile organic compounds.

As part of this effort, the California Air Resources Board funded Dr. Wexler, a co-PI of this proposal, to develop a cost-effective instrument to measure toxic metals in the air. Conventional toxic metal instruments cost about $200,000, while Dr. Wexler’s instrument has similar performance but only costs $3,000 to build. With US EPA funding, Dr. Wexler is also developing an inexpensive instrument for measuring toxic VOCs. Conventional instruments that measure these compounds cost on average over $500,000. Dr. Wexler’s instrument will cost about $20,000.

Assessing toxic volatile organic compound exposures with gas chromatograph, cross flow ion mobility spectrometry

Principal Investigators: Anthony Wexler, Tom Young, and Jonathan London
Funded by EPA

Currently, there are no portable, modest-cost instruments for measuring volatile organic compounds (VOCs) in the atmosphere that are hazardous air pollutants (HAPs). The objective of this project is to develop such an instrument and deploy it in cooperation with underrepresented communities who have VOC HAPs in the air they breathe. There are many thousands of volatile organic compounds in the atmosphere. Over a hundred are toxic and included on EPA’s HAPs list. With so many VOCs in the atmosphere, techniques are needed to separate the toxic ones from the benign ones. The conventional approach is gas chromatography followed by mass spectrometry, so-called GC-MS. But mass spectrometry requires high vacuum, is heavy and requires a lot of power.

The approach in this project is to use gas chromatography followed by ion mobility spectrometry (IMS) instead of mass spectrometry, so called GC-IMS. Conventional IMS has relatively low mobility resolution. We have developed a type of IMS called cross-flow ion mobility spectrometry (CF-IMS) that has about 8 times the mobility resolution of conventional IMS.

Synergistic effects of stress and traffic-related air pollution on cardiovascular health

Principal Investigators: Anthony Wexler, Chao-Yin Chen and Jane Ellen
Funded by NIEHS

Cardiovascular disease (CVD), the leading cause of death in the U.S., disproportionately impacts persons of lower socioeconomic position (SEP) -- a disparity that has been attributed to heightened exposures to both traffic- related air pollution (TRAP) and chronic social stressors. Studies have shown that exposures to chronic stress can vastly increase susceptibility to TRAP, though growing evidence now suggests that TRAP may also strongly impact hypothalamic-pituitary-adrenal (HPA)-axis function and acute stress response, complicating the interactions.

In this ViCTER proposal, we will quantify and compare chronic and acute stress, TRAP, and their multiple interactions, in shaping cardiovascular function. We are uniquely poised to map this unexplored terrain, as accomplished senior investigators in atmospheric science and mechanical engineering (Wexler), cardiovascular regulation and autonomic function (Chen), and exposure science and social-environmental epidemiology (Clougherty). We will use a unique TRAP delivery system with real-time concentration and chemical composition measures, time-resolved measures of cardiovascular function (telemetry), and biological profiling at multiple time points for chronic and acute stress markers (e.g., cortisol, CRP, cytokines). We hypothesize that: (1) TRAP composition (light- vs. heavy-duty vehicles) differently impact cardiovascular function; (2) Chronic stress may heighten cardiovascular response to TRAP, over the course of study; (3) TRAP may compromise cardiovascular resilience to stress challenge.

Do atmospheric ultrafine particles lodge in the brain and cause cognitive decline leading to Alzheimer's disease related dementias?

Principal Invesitgators: Pamela Lein, Charles DeCarli and Michael Kleeman
Funded by NINDS

There is growing consensus that environmental factors influence risk for Alzheimer’s disease and Alzheimer’s disease-related dementias (AD/ADRD). Consistent with this hypothesis, cognitive trajectories of participants in the UC Davis Alzheimer’s Disease Research Center (UCD ADRC) Longitudinal Diversity Cohort (LDC) differ geographically. These geographical differences may arise from differential exposures to environmental contaminants.

In this translational study, we will test our central hypothesis that ultrafine particulate matter (UFPM) enters the brain of exposed individuals and increases risk of cognitive decline and incident AD/ADRD. Studies have largely focused on PM2.5 (fine particulate matter with an aerodynamic diameter < 2.5 µm) in AD/ADRD risk. UFPM is a subset of PM2.5. Because of its smaller size (< 0.1 µm), inhaled UFPM can cross biological barriers to gain access to multiple organs, including the brain. Data from this project will identify AD/ADRD-relevant neuropathology associated with UFPM.

Additionally, this project addresses (1) biological plausibility and clinical relevance of UFPM in air pollution as an environmental factor that modifies AD/ADRD initiation and progression and contributes to AD/ADRD racial/ethnic disparities; (2) AD/ADRD models of exposure; and (3) generation of data needed to support public health and regulatory strategies for controlling key sources of UFPM associated with AD/ADRD.

Traffic-related air pollution exacerbates AD-relevant phenotypes

Principal Investigators: Pam Lein, Laura Van Winkle, Keith Bein
Funded by NIA

Alzheimer’s disease (AD) is the most prevalent age-related neurodegenerative disease in the United States. More than 90% of cases are idiopathic and there is growing consensus that gene x environment interactions influence the age of onset and progression of this disease. Preclinical studies support a causal relationship between TRAP and increased AD risk, but many of these studies used concentrated ambient particles or diesel exhaust that do not recapitulate the complexity of current real-world TRAP exposures.

We have designed a unique exposure model using real-time exposure to TRAP collected from a major freeway tunnel system, which preserves the gaseous and particulate components of real-world TRAP and captures daily fluctuations in pollutant levels. We will leverage this model to test our central hypothesis that TRAP decreases the time to onset and/or increases severity of AD-like phenotypes via microglial cell activation secondary to lung inflammation by addressing the following specific aims: (1) Determine which vehicle emission component(s) cause neuroinflammation and neurodegeneration; and (2) Investigate the role of the lung-brain axis in mediating TRAP effects on AD phenotypes. Our broad long-term objectives are to inform regulatory and health interventions aimed at reducing AD risk for individuals living, working, or attending school near busy roadways.