Frailty status modifies the association between air pollution and post-myocardial infarction mortality: a 20-year follow-up study.

To the Editor: Exposure to air pollution is virtually ubiquitous, and has been associated with the development of a multitude of chronic illnesses. We have previously shown that chronic exposure to particulate matter ≤2.5 μm in diameter (PM2.5) is associated with an increased risk of