Grantee Research Project Results

During the past year under Award CR83998101, HEI has made substantial progress in meeting its goals. HEI is actively managing and reviewing over 30 studies on a variety of relevant topics. Furthermore, HEI issued three requests for applications (RFAs) and one request for qualifications (RFQ), initiated or recommended nine new studies for funding, and held a workshop to identify priorities for research funding. A list of ongoing studies (as of March 31, 2024) is provided in Table 1 (attached). Highlights of HEI activities are provided below.

Accountability: Testing the Links Between Air Quality Actions and Health

• Under its accountability program, three studies — one to quantify monetized societal health benefits associated with emissions reductions in major source sectors, a second to evaluate a national school bus diesel retrofit program, and a third to assess national and local programs to reduce emissions from motor vehicles in Houston, Texas — were in the final publication stage. Two studies that evaluated changes in health and air pollution associated with Chinese national policies to reduce emissions were completed; investigators began preparing final reports. Two studies — one comparing the effects of selected policies that targeted mobile vehicles and electricity generating units to improve air quality and another developing national, fine-scale, daily PM2.5 source impact exposure estimates — continued to make good progress

Complex Questions for the Air Pollution Mixture

• Research on air pollution exposure and COVID-19 health outcomes made substantive progress during this reporting period. One study to investigate the association between air pollution and risk of severe outcomes in the Danish population completed review and was published. The remaining four studies – one evaluating the interaction between long-term air pollution exposure and neighborhood vulnerability to adverse COVID-19 outcomes, a second investigating the risk of severe outcomes in a Spanish population, a third assessing the relationship between air pollution exposure and COVID-19 incidence, complications, and mortality in a U.S. population, and a fourth investigating the effect of pandemic lockdowns on air quality and health outcomes — were completed and entered the review process.
• Under research that falls within the broader HEI Strategic Plan 2020-2025 but outside major RFA topics, two studies of wildfires and agricultural burning continued to make substantive progress during this reporting period.
• To inform decisions on future research on particulate matter, HEI held a workshop in December 2023. Sessions were (1) Biologic Plausibility at Chronic Low-Dose Exposure, (2) The Role of the Indoor Environment in Evaluating the Health Effects of Outdoor Air Pollution, (3) Health Effects of Episodic Air Pollution Events: Case Studies of Fire Smoke, and (4) Emerging Particulates. Several breakout sessions were conducted to identify top research priorities, and the presentations and extensive discussions will be used to inform a new RFA.
• Additional research is funded through our Rosenblith New Investigator Award to support researchers at the early stages of their careers. In the category of biological mechanisms, one study investigating the role of reactive oxygen species in inflammation completed review and was published, and another study investigating the relationship between air pollution exposures and changes in the gut microbiome in infants continued to progress. In the category of multipollutant epidemiology, several studies made substantive progress. A study investigating the association between air pollution exposure and asthma in Danish cohorts and another study assessing the relationship between air pollution exposure and prefrontal connectivity and behavioral outcomes in adolescents completed review and entered the publication stage. A study examining the effects of long-term exposure to ultrafine particles on several mortality and morbidity outcomes was completed, and preparation of the final report was begun. A final study that is developing statistical methods for analyzing complex air pollution mixtures and health outcomes by using causal inference-based approaches continued to make substantive progress. In the category of marginalized communities, two studies — one developing statistical methods to characterize spatial and racial/ethnic variation in health effects associated with exposure to fine particulate matter and another advancing a community–academic partnership to characterize sources of air pollution and identify community-driven solutions through an emissions reduction plan — were initiated.

Transport and Urban Health

• During the last reporting period, HEI issued an RFA, Assessing Health Effects of Traffic- Related Air Pollution (TRAP) in a Changing Urban Transportation Landscape. During this reporting period, applications were reviewed, and four studies were recommended for funding and initiated. These studies aim to create a framework for full-chain assessment of transportation systems and the effects of TRAP on population health; examine associations of TRAP with lipids and other biomarkers to explore pathways that might mediate cardiovascular disease risk; assess consequences of future urban transportation landscapes on cardiometabolic health; and develop models for relating exposures from vehicle, rail, and aircraft sources to birth outcome data.
• To guide improvements in air pollution exposure assessment, three studies investigating strategies to enhance exposure assessment and two studies quantifying the influence of exposure measurement error entered the review process; one of these is in the publication stage. The overall goals of this program are to develop approaches that can be applied to long-term epidemiology studies and to assess the benefit of increasingly sophisticated models and approaches.
• To improve our understanding of exposure and health effects from TRAP, research was completed for three studies that evaluated the influence of noise, green space, and socioeconomic status; all three studies entered review during this reporting period. A New Investigator study that focused on mobile monitoring campaigns using Google street-view cars completed the review process and was published this reporting period.
• To investigate the importance of non-tailpipe emissions, two studies that were initiated during the last reporting period made substantive progress this reporting period. One is assessing short-term respiratory health effects in non-smoking adults with mild to moderate asthma during and after sequential exercise exposures to three contrasting air quality environments in London, United Kingdom. The other is conducting real-world field measurements to estimate and understand population exposure to non-tailpipe versus tailpipe particulate matter.
• To address questions about the impacts of the turnover of the legacy fleet to cleaner vehicle technologies, HEI formed a panel of six experts to assess the potential benefits of accelerated heavy-duty diesel fleet turnover. A Request for Qualifications (RFQ) was issued in March 2024 with the following objectives: (1) identify an urban hotspot in the United States that might benefit from fleet turnover, (2) quantify potential benefits of accelerating medium- and heavy-duty diesel vehicle fleet turnover in the selected hotspot, and (3) identify challenges or barriers to replacement of the older vehicles through active engagement with owners and operators of medium- and heavy-duty vehicles and other audiences.

Detailed information on the ongoing studies described above can be found here: https://www.healtheffects.org/research/ongoing-research

Environmental Justice

• During the last period, HEI reported that it had launched a new research program in environmental justice; for more information, see https://www.healtheffects.org/about/environmental-justice-program. Work continued this reporting period with issuing RFA 23-2, Assessing Changes in Exposures and Health Outcomes in Historically Marginalized and Environmentally Overburdened Communities from Air Quality Actions, Programs, or Other Interventions. This RFA was modeled after HEI’s long history of funding accountability research to assess the effects of air quality actions on health outcomes. Applications were reviewed, and three studies were recommended for funding. Contract initiation is underway.
• Building on recommendations from the workshop that was held in October 2022 (see https://www.healtheffects.org/meeting/workshop-new-science-inform-environmental- justice), HEI issued RFA 24-1, Cumulative Impact Assessment For Decision-Making: A Community–Academic Partnership Approach. The objective of this RFA is to strengthen community–academic partnerships and conduct cumulative impact assessments where results can inform a specific decision context. The RFA is structured such that partnership strengthening and problem formulation are funded in one phase, and the research implementation and translation are funded in a second phase. Applicants are allowed to apply directly to the second phase. Applications will be reviewed, and funding decisions made in the next reporting period.