Literature Search Strategy

We conducted this meta-analysis in accordance with the Preferred Reporting Items for Systematic Reviews and Meta-Analysis (PRISMA) (16) and the checklist of items in the Meta-Analysis of Observational Studies in Epidemiology (MOOSE) (17). A systematic literature search of PubMed and Embase was conducted through September 2019 by using the following search terms with no restrictions: “air pollution” or “particulate matter” or “air pollutants” or “PM₁₀”or “PM_2.5” or “air quality” in combination with “myocardial infarction” or “heart attack” or “acute coronary syndrome” or “cardiovascular disease” or “heart disease.” The language was restricted to English. Additionally, reference lists of the retrieved original articles and relevant review articles were also scrutinized to identify further pertinent studies.