Size-specific health effects of particulate matter components on cardiovascular mortality: a weekly time-series study...

Most evidence on the cardiovascular effects of particulate matter has focused on total mass concentration or fine particulate matter (PM_2.5), whereas less is known about how particle size and chemical composition jointly shape cardiovascular risk. We conducted a weekly time-series study in Tianjin, China, to examine the associations of total particulate matter mass across nine size fractions and 23 size-specific components with cardiovascular mortality during 2019-2022. Generalized linear models with a quasi-Poisson distribution were used to estimate the excess risk (ER) associated with an interquartile range increase in exposure, with further analyses by cardiovascular disease (CVD) subtype, sex, and age, and additional adjustment for ozone (O₃) and nitrogen dioxide (NO₂). Positive associations for total particulate matter mass were concentrated mainly within the 0-3.3 μm range, peaking at 1.1-2.1 μm. Component-specific associations also varied across particle-size fractions and were clustered predominantly in finer particles. Chloride (Cl^-), potassium (K), chromium (Cr), titanium (Ti), and cadmium (Cd) showed the most prominent associations. Ischemic heart disease involved more significant components and a wider size range than stroke. These findings indicate that cardiovascular mortality is shaped by cross-dimensional patterns of particle size and components and support more refined risk identification beyond total mass alone.