PM_2.5 constituents and hospitalizations of full-spectrum cardiovascular diseases: A national case-crossover study

Multicenter evidence remains limited regarding the short-term impacts of fine particulate matter (PM_2.5) constituents on specific cardiovascular disease (CVD) outcomes. This study assessed the short-term links between PM_2.5 chemical constituents and CVD hospitalizations in China. Hospitalization data for 10 broad categories and 40 cause-specific CVD outcomes were collected from 153 hospitals across 20 provinces in China during 2013-2020. A time-stratified case-crossover design was applied. Five major constituents of PM_2.5, namely black carbon, organic matter (OM), sulfate (SO₄^2-), nitrate (NO₃^-), and ammonium, were extracted from the Tracking Air Pollution datasets. PM_2.5 and its constituents were associated with higher hospitalization risk for six CVD categories: hypertensive diseases, ischemic heart diseases, pulmonary heart diseases, cerebrovascular diseases, diseases of veins, lymphatic vessels and lymph nodes, and other forms of heart disease. The largest effect estimates were observed on lag 0-1 day, ranging from 0.72% to 4.87% per interquartile range increase in PM_2.5 and its constituents. Significant associations were also observed for 15 specific causes of CVDs. OM, SO₄^2-, and NO₃^- generally showed larger effect estimates than the other constituents. The concentration-response curves exhibited mostly positive trends. Associations were stronger among males and elderly people, and during the cold season. This nationwide study offers insights into the effects of PM_2.5 constituents on CVD hospitalizations, highlighting the necessity for targeted control of these PM_2.5 constituents.