Background Higher ambient fine particulate matter (PM_2.5) levels can be associated with increased blood pressure and vascular dysfunction.

Objectives To determine the differential effects on blood pressure and vascular function of daily changes in community ambient- versus personal-level PM_2.5 measurements.

Methods Cardiovascular outcomes included vascular tone and function and blood pressure measured in 65 non-smoking subjects. PM_2.5 exposure metrics included 24 h integrated personal- (by vest monitors) and community-based ambient levels measured for up to 5 consecutive days (357 observations). Associations between community- and personal-level PM_2.5 exposures with alterations in cardiovascular outcomes were assessed by linear mixed models.

Results Mean daily personal and community measures of PM_2.5 were 21.9±24.8 and 15.4±7.5 μg/m³, respectively. Community PM_2.5 levels were not associated with cardiovascular outcomes. However, a 10 μg/m³ increase in total personal-level PM_2.5 exposure (TPE) was associated with systolic blood pressure elevation (+1.41 mm Hg; lag day 1, p<0.001) and trends towards vasoconstriction in subsets of individuals (0.08 mm; lag day 2 among subjects with low secondhand smoke exposure, p=0.07). TPE and secondhand smoke were associated with elevated systolic blood pressure on lag day 1. Flow-mediated dilatation was not associated with any exposure.

Conclusions Exposure to higher personal-level PM_2.5 during routine daily activity measured with low-bias and minimally-confounded personal monitors was associated with modest increases in systolic blood pressure and trends towards arterial vasoconstriction. Comparable elevations in community PM_2.5 levels were not related to these outcomes, suggesting that specific components within personal and background ambient PM_2.5 may elicit differing cardiovascular responses.