Global association between ambient air pollution and blood pressure: A systematic review and meta-analysis.

Although numerous studies have investigated the association of ambient air pollution with hypertension and blood pressure (BP), the results were inconsistent. We performed a comprehensive systematic review and meta-analysis of these studies. Seven international and Chinese databases were searched for studies examining the associations of particulate (diameter<2.5 μm (PM 2.5 ), 2.5–10 μm (PM 2.5-10 ) or >10 μm (PM 10 )) and gaseous (sulfur dioxide (SO 2 ), nitrogen dioxide (NO 2 ), nitrogen oxides (NO x ), ozone (O 3 ), carbon monoxide (CO)) air pollutants with hypertension or BP. Odds ratios (OR), regression coefficients (β) and their 95% confidence intervals were calculated to evaluate the strength of the associations. Subgroup analysis, sensitivity analysis, and meta-regression analysis were also conducted. The overall meta-analysis showed significant associations of long-term exposures to PM 2.5 with hypertension (OR = 1.05), and of PM 10 , PM 2.5 , and NO 2 with DBP (β values: 0.47–0.86 mmHg). In addition, short-term exposures to four (PM 10 , PM 2.5 , SO 2 , NO 2 ), two (PM 2.5 and SO 2 ), and four air pollutants (PM 10 , PM 2.5 , SO 2 , and NO 2 ), were significantly associated with hypertension (ORs: 1.05–1.10), SBP (β values: 0.53–0.75 mmHg) and DBP (β values: 0.15–0.64 mmHg), respectively. Stratified analyses showed a generally stronger relationship among studies of men, Asians, North Americans, and areas with higher air pollutant levels. In conclusion, our study indicates a positive association between ambient air pollution and increased BP and hypertension. Geographical and socio-demographic factors may modify the pro-hypertensive effects of air pollutants. [ABSTRACT FROM AUTHOR]