Higher Risk of Cardiovascular Disease Associated with Smaller Size-Fractioned Particulate Matter

No nationwide studies have examined the associations between mortality risk and PM₁ (PM with an aerodynamic diameter of <1 μm) due to the scarcity of monitoring data of PM₁. On the basis of newly released national scale PM₁ data, we performed a time series analysis to elucidate the cause-specific mortality risk caused by PM₁ exposure in China. During the period from January 2014 to December 2017, the PM₁ levels in 65 cities of China were on average 37 ± 32 μg/m³. Pooled results indicated a 10 μg/m³ increase in the PM₁ level was associated with a 0.19% [95% confidence interval (CI) of 0.09–0.28%] increased risk in nonaccidental mortality, which was almost the same as that for PM_2.5 (0.18%, 95% CI of 0.08–0.27%) and PM₁₀ (0.17%, 95% CI of 0.01–0.24%). By comparison, the magnitude increased to 0.29% (0.12–0.47%) in cardiovascular disease for each 10 μg/m³ uptick in PM₁, which was significantly higher than that related to PM_2.5 and PM₁₀ exposure. This nationwide study supported the notion that PM₁ may be a higher risk factor for cardiovascular disease, which suggests rapid action is warranted to put more effort into mitigating the emissions of finer particulate matters.