Would alternative control strategies have significant impacts on the magnitude or distribution of particulate matter health impacts?
Within this document, I address these three questions in greater detail, summarizing the key studies that inform my answers to these questions. Along with this summary document, I have included copies of selected documents that provide even more information about the core issues. Is there a threshold? An initial point that is important to emphasize is that this is not the same question as whether PM2.5 concentrations are above or below National Ambient Air Quality Standards. Quoting directly from the US EPA in their Final Rule for the PM2.5 NAAQS, The Act does not require the Administrator to establish a primary NAAQS at a zero-risk level, but rather at a level that reduces risk sufficiently so as to protect public health with an adequate margin of safety. (p. 3). The question is therefore whether the health literature provides evidence of a threshold above current ambient concentrations. First considering time-series studies, which evaluate the effects of changes in daily concentratio
