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 PM and BP, while most of those focused on low or medium PM concentration. The aim of this study was to reveal the association between extremely high level ambient PM 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 PM 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 PM and daily variations in BP. This study showed short-term exposure to PM 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 PM on DBP had a 2-day lag, and the cumulative effect lags 5 days. The effects of PM on SBP and DBP on hypertensive adults were significant. The cumulative effect of PM 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 PM may increase BP among adults. Hypertensive adults may more sensitive than normotensive adults. The periodic high concentration of ambient PM might magnify the effect of PM on BP increase.