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HEI is reviewing initial findings from “low exposure levels” research

November 2018

HEI is reviewing and plans to publish the first results from a study on health effects at low levels of air pollution. The study is expected to be relevant to an ongoing review by the U.S. Environmental Protection Agency (EPA) of the federal standard for allowable concentrations of fine particulate matter in the air. It is one of three comprehensive studies that HEI is funding to examine the possible health effects from exposure to pollutants at low concentrations. (See HEI Update - Fall 2015.)

Levels of ambient air pollution have declined significantly over the last decades in North America, Europe, and other high-income regions. Nonetheless, as discussed in HEI’s Strategic Plan for 2015–2020, some epidemiological studies have reported associations with adverse health effects even at these lower levels of exposure. To inform future risk assessment and regulation, it is important to know whether adverse effects continue to be observed as levels of air pollution decline still further and what the shape of the exposure–response function is at those low levels. In 2016, as part of the Strategic Plan, HEI funded three studies that will evaluate large populations in North America and Europe to delve into these important questions. One of these studies is being led by Francesca Dominici at the Harvard T.H. Chan School of Public Health. During the first two years of this four-year study, Dominici and her colleagues have published initial results that have the potential to be important both scientifically and in the context of policy. 

The EPA is currently on an accelerated track to review the National Ambient Air Quality Standard (NAAQS) for PM2.5 (particulate matter ≤ 2.5 in aerodynamic diameter), and HEI believes that Dominici’s results, as well as thoughtful comments from HEI’s review of them, can play a constructive role. With that in mind, HEI requested, and the investigators have now submitted, a Phase 1 report — summarizing their key analyses, findings and interpretations — based on the research completed so far. HEI plans to rigorously review and publish Phase 1, with a commentary, in time for EPA’s consideration during the standard setting process.

As it often does when reviewing particularly complex studies, HEI has formed a special panel to review the Phase 1 report for this purpose. Sverre Vedal of the University of Washington, Seattle — former member of the HEI Review Committee and chair of the HEI panel to review the Revised Analyses of Time-Series Studies of Air Pollution and Health (2003 Special Report) —  will chair this new panel, which will also include six experts in epidemiology, exposure assessment, and biostatistics. HEI anticipates publishing the Phase 1 investigators’ report, along with the special panel’s commentary, in the spring of 2019. 

For more information on all three low exposure epidemiology studies, see Ongoing Research.