The association between short-term exposure to extremely high level of ambient fine particulate matter and blood pressure: a panel study in Beijing, China.

: High blood pressure (BP) is known as the main determinant of high cerebrovascular disease levels in China. Many studies discovered the associations between short-term exposure to PM2.5 and BP, while most of those focused on low or medium PM2.5 concentration. The aim of this study was to reveal the association between extremely high level ambient PM2.5 exposure and BP. We conducted a repeated-measures panel study in Beijing, China, during December 1, 2016 to December 28, 2016. BP was monitored daily for all 133 participants. Daily concentration of PM2.5 was obtained from local monitoring sites. A linear mixed-effect model combined with the distributed lag non-linear model was used to evaluate the associations between PM2.5 and daily variations in BP. This study showed short-term exposure to PM2.5 that was significantly associated with increased DBP (on lags of 0-8 days, Beta = 0.12, 95% confidence interval 0.04, 0.20). The single day effect of PM2.5 on DBP had a 2-day lag, and the cumulative effect lags 5 days. The effects of PM2.5 on SBP and DBP on hypertensive adults were significant. The cumulative effect of PM2.5 on SBP and DBP had 2 rapidly increasing periods in hypertensive adults: lags of 0-2 days and lags of 0-7 days to lags of 0-11 days. Our study revealed that short-term exposure in the extreme high level of ambient PM2.5 may increase BP among adults. Hypertensive adults may more sensitive than normotensive adults. The periodic high concentration of ambient PM2.5 might magnify the effect of PM2.5 on BP increase.