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Quantitative Characterization of Uncertainty in the Concentration–Response Relationship between Long-Term PM2.5 Exposure and Mortality at Low Concentrations
journal contribution
posted on 2020-08-06, 14:17 authored by Evan Coffman, Richard T. Burnett, Jason D. SacksExtensive
epidemiologic evidence supports a linear, no-threshold
concentration–response (C-R) relationship between long-term
exposure to fine particles (PM2.5) and mortality in the
United States. While examinations of the C-R relationship are designed
to assess the shape of the C-R curve, they do not provide the information
needed to quantitatively characterize uncertainty at specific PM2.5 concentrations, which is often needed in the context of
risk assessments and benefits analyses. We developed a novel approach,
using information that is typically available in published epidemiologic
studies, to quantitatively characterize uncertainty at different concentrations
along the PM2.5 concentration distribution. Our approach
utilizes the annual mean PM2.5 concentration and corresponding
standard deviation from a published epidemiologic study to estimate
the standard deviation of hypothetical PM2.5 concentration
distributions defined at 0.1 μg/m3 increments. The
hypothetical distributions are then used to derive adjusted uncertainty
estimates in the reported effect estimate at low concentrations (i.e.,
concentrations lower than the annual mean observed in the study).
We demonstrate the application of this method in six individual epidemiologic
studies that examined the relationship between long-term PM2.5 exposure and mortality and were conducted in different geographic
locations worldwide and at different PM2.5 concentrations.
This new method allows for a more comprehensive quantitative evaluation
of uncertainty in the shape of the C-R relationship between long-term
PM2.5 exposure and mortality at concentrations below the
mean annual concentrations observed in current studies.