Acute effects of ambient particulate matter on blood pressure: differential effects across urban communities

Recent studies have suggested a link between exposure to ambient particulate matter <2.5 microm in diameter (PM(2.5)) and adverse cardiovascular outcomes. The objective of this study was to examine the effects of differing community-level exposure to PM(2.5) on daily measures of blood pressure (BP) among an adult population. During the period May 2002 through April 2003, BP was examined at 2 time points for 347 adults residing in 3 distinct communities of Detroit, Michigan. Exposure to PM(2.5) was assessed in each community during this period, along with multivariate associations between PM(2.5) and BP. In models combining all 3 of the communities, PM(2.5) was significantly associated with systolic blood pressure; a 10-microg/m(3) increase in daily PM(2.5) was associated with a 3.2-mm Hg increase in systolic blood pressure (P=0.05). However, in models that added a location interaction, larger effects were observed for systolic blood pressure within the community with highest PM(2.5) levels; a 10-microg/m(3) increase in daily PM(2.5) was associated with a 8.6-mm Hg increase in systolic blood pressure (P=0.01). We also found young age (<55 years) and not taking BP medications to be significant predictors of increased BP effects. Among those taking BP medications, the PM(2.5) effect on BP appeared to be mitigated, partially explaining the age effect, because those participants <55 years of age were less likely to take BP medications. Short-term increases in exposure to ambient PM(2.5) are associated with acute increases in BP in adults, especially within communities with elevated levels of exposure.