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Ongoing Research
At any given time, HEI has a variety of ongoing studies at various stages of completion. Here, you will find a list of studies with more detailed information for each, including abstracts and posters presented at HEI Annual Conferences. We also indicate which studies have been completed and are currently undergoing HEI’s rigorous review process.

Ongoing Studies
Accountability Studies
This study will evaluate the National Clean Diesel Rebate Program, a lottery program that allocates available funding to school districts across the United States to replace or retrofit old-technology diesel powered school buses. Adar and colleagues will compare student health and educational performance in districts with and without such funding.
The investigators will develop and apply a source‐ and location-specific database of mortality benefits per ton emissions reduction of NOx and other pollutants.
This study will focus on a coal ban and heat pump subsidy program in the Beijing, China, region. They are building on an existing panel study that is following about 966 people who live in 50 villages around Beijing. Half the villages are subject to the policy, the other half are not.
This study will assess the effects of emission-control measures on birth outcomes associated with traffic-related air pollution in Texas. Hystad and colleagues will evaluate air quality changes associated with national motor vehicle emissions regulations, as well as a diverse array of local congestion reduction programs implemented in Texas over the past 25 years.
This study will evaluate the major national regulatory policies that were implemented in China from 2008–2018. The investigators will focus on regulations in particular regions that target specific sources, such as coal combustion, and how they have reduced ambient concentrations of fine particles (and their components).
In this HEI-funded project, the investigators will build on their previous accountability analyses in Atlanta, New York, and Los Angeles to characterize the health impacts of MV and EGU policy implementation.
COVID-19, Air Pollution, and Health Studies
This study will investigate whether exposure to air pollution increases the risk of severe COVID-19 outcomes, and identify the most susceptible groups by socioeconomic status, ethnicity, and comorbidities. Between March and December 2020, the investigators followed more than 3 million adults in Denmark. They will evaluate whether long- (40 years) and short- (1 year) term exposure to several common air pollutants increased the risk of COVID-19 hospitalization and mortality.
This multicountry study will evaluate whether changes in mortality are associated with changes in ambient NO2 and PM2.5 levels before, during, and after the lockdown and disentangle the short-term effects of NO2 versus PM2.5 on mortality. The analysis will be conducted in four countries: China, Germany, Italy, and the United States.
This study will investigate the chronic and acute effects of air pollution exposure on COVID-19 incidence, mortality, and long-term complications, including onset of disease formation. Long- (2017−2018) and short- (2020) term exposures will be linked to a large medical records database in Southern California, with assessments at both the neighborhood and individual level.
In this study the investigators will conduct a retrospective evaluation of the interactions between long-term exposure to air pollution and neighborhood vulnerability to adverse COVID-19 outcomes. They will investigate both single and multipollutant air pollution exposures in relation to COVID-19 hospitalization, inpatient length of stay, ICU admission, ventilator use, and death among a racially diverse population in New York City.
This study will test whether long- or short-term exposure to air pollution increases the risk of COVID-19 hospital admissions or mortality and identify vulnerable subgroups among 6 million residents of Catalonia, Spain. The investigators will link air pollution exposures to residents’ addresses and inpatient and outpatient electronic medical records.
Enhanced Exposure Studies
This study aims to improve our understanding of the contribution of individual mobility in air pollution exposure estimates. The investigators will use location tracking on a mobile phone application for 2,000 individuals in the Netherlands and Switzerland.
Hoek and colleagues will prepare maps of modeled annual average air pollution across the Netherlands, validate the maps using new measurements from over 100 sites, and evaluate the performance of several exposure models. The investigators will conduct cross-comparisons to evaluate how different exposure assessment methods compare in their ability to predict long-term pollutant concentrations, with a particular focus on spatial variability of pollutants.
This study will investigate the consequences of measurement error on estimates of health effects of long-term exposure to outdoor air pollution in London by developing increasingly sophisticated exposure models.The investigators plan to compare exposure models that account for mobility, are based on exposure estimates at the residential address, and are based on concentrations measured at the nearest air pollution monitor.
This study will compare and contrast scientific and logistical benefits of different approaches to air pollution exposure assessment. The investigators will leverage large air pollution datasets obtained from low-cost sensors, mobile monitoring, and passive samplers. They will apply the exposure assessment approaches to determine associations with cognitive decline and dementia incidence in an ongoing cohort study, Adult Changes in Thought Air Pollution (ACT-AP).
This study will evaluate health impacts of long-term exposures to traffic-related air pollution using exposure estimates from fixed-site and mobile measurement campaigns, as well as deep learning models, in Toronto and Montreal, Canada. The investigators will compare exposure estimates generated by these models to present-day and historical measurements, and to each other.
Global Health Studies
This study is estimating global ambient annual average NO2 concentrations and associated pediatric asthma at high spatial resolution (100m x 100m) for incorporation into the Global Burden of Disease Study (GBD). The investigators will improve methods to estimate trends in surface NO2 concentrations from 1990 to 2018 and will update a systematic review of the epidemiological literature on NO2 and incidence of pediatric asthma to assess related worldwide burden of disease.
Quantifying Real-World Impacts of Non-Tailpipe Particulate Matter Emissions
In this study, participants with mild to moderate asthma will ride stationary bicycles on sidewalks in three London, UK environments (busy road characterized by stop-and-go traffic, high speed continuous traffic, and urban background) to measure how exposure to traffic with different mixtures of non-tailpipe and tailpipe emissions affects lung function of asthmatic adults.
This study will measure concentrations of non-tailpipe particulate matter across Toronto, Canada to determine how much non-tailpipe pollution people might breathe in everyday life and how to better measure these exposures in the future.
Traffic Exposure and Health Studies
In this study, the investigators will recruit pregnant women in Barcelona and assess the effects of in-utero exposure to traffic-related pollution on birth weight, fetal growth trajectories, and placental function for each pregnancy. The investigators will estimate exposure to several pollutants and transportation noise and evaluate the roles of socioeconomic status, green space, physical activity, diet, and stress.
This study will assess the effects of metals from nontailpipe emissions on asthma and lung function in the most recent cohort of the Children’s Health Study in Southern California (recruited during 2002-2012), using available filters with particulate matter samples. The investigators will estimate exposure to several pollutants and transportation noise and evaluate the roles of socioeconomic status, green space, physical activity, diet, and stress.
This study will assess myocardial infarction, stroke, diabetes, and biomarkers related to cardiovascular disease and diabetes in three large Danish cohorts. The investigators will estimate exposure to several pollutants and transportation noise and evaluate the roles of socioeconomic status, green space, physical activity, diet, and stress.
Wildland Fires and Agricultural Burning Studies
This study is investigating risk of birth outcomes and perinatal mortality from fire-related PM2.5. The interdisciplinary team is developing fire modeling methods to estimate PM2.5 specifically from fires for Australia with improved fire emissions inventories and Lagrangian modeling.
The objectives of this study are to: 1) Estimate the contributions of prescribed burning to both fine particulate matter (PM2.5) and ozone (O3) levels in the Southeastern US; 2) Quantify the effects of prescribed fire smoke on rates of emergency department (ED) visits; and 3) Assess how the observed health impacts vary across strata defined by age, sex, and socioeconomic markers.
Walter A. Rosenblith Award
This New Investigator Award study will investigate whether prenatal and/or early-life exposure to air pollutants affects the infant gut microbiota and fecal metabolome, thereby altering infant growth trajectories in the first two years of life. Dr. Alderete plans to study this in an ongoing longitudinal cohort of Hispanic mother-infant pairs in California with existing validated clinical assessments of infant growth trajectories. She will also use gut microbial profiling and high-resolution fecal metabolomics profiles to understand the mechanisms underlying the obesogenic effects of air pollutants in early life.
This New Investigator Award study seeks to provide novel exposure–response functions for the effects of long-term exposure to ultrafine particles on several mortality and morbidity outcomes, while adjusting for exposures to other traffic-related air pollutants, road traffic noise, and socioeconomic status. The study makes use of a new Danish cohort of 650,000 adults.
This New Investigator Award study seeks to develop statistical methodology that allows for complex relationships between air pollution and health outcomes to be used to estimate causal effects of multivariate exposures. Additionally, the proposed methodology will allow for evaluation of separate subgroups in the population to identify the most vulnerable subgroups.
This New Investigator Award study will measure air pollutants in intensive campaigns with Google Street View cars in Oakland and Delhi and compare exposure estimates to conventional methods.
This New Investigator Award study seeks to examine associations of long-term maternal exposures to PM2.5, NO2, and environmental noise with adverse birth outcomes in Accra, Ghana. The investigators also seek to determine the effect of these exposures on the risk of lower respiratory infections in infants.
The primary objective of this Walter A. Rosenblith New Investigator Award study is to create fine-scale daily PM2.5 source impacts from major source and fuel categories from 2011-2020. This objective builds on recent work developing fine-scale daily air pollution exposure products in the United States, which have driven recent epidemiological studies on air pollution health effects.
This New Investigator Award study is evaluating how fine-particle exposure affects the development of prefrontal connections and emotional behaviors during the transition from childhood to adolescence and whether this, in turn, contributes to greater risk for neuropsychiatric disorders.
This New Investigator Award study will evaluate whether air pollution is associated with increased incidence of asthma in 3 cohorts in Denmark.
This New Investigator Award Study investigates the mechanisms of formation of reactive oxygen species (ROS) by different types of secondary organic aerosols (SOAs), distinguishing between ROS formed by pollutants entering lung lining fluid (chemically) and by macrophages producing ROS as an inflammatory response (biologically). He will measure concentrations of ROS in epithelial lung lining fluid in macrophages exposed to SOA produced in a reaction chamber, with or without transition metals, using electron paramagnetic resonance spectroscopy with a spin trapping technique or a chemiluminescence assay.