A community study of the effect of particulate matter on blood measures of inflammation and thrombosis in an elderly population

Background: The mechanism behind the triggering effect of fine particulate matter (PM) air pollution on cardiovascular events remains elusive. We postulated that elevated levels of PM would be associated with increased blood levels of inflammatory and thrombotic markers in elderly individuals. We also hypothesized that elevated PM would increase levels of cytokines in individuals with heart disease. Methods: We measured these blood markers in 47 elderly individuals with (23) and without (16 COPD and 8 healthy) cardiovascular disease (CVD) on 2 or 3 mornings over a 5 or 10-day period between February 2000 and March 2002. Blood measures were paired with residence level outdoor PM measured by nephelometry. Analyses determined the within-individual effect of 24-hour averaged outdoor PM on blood measures. Results: Analyses found no statistically significant effect of a same day 10 ug/m3 increase in fine PM on log transformed levels of CRP 1.21 fold-rise [5% CI: 0.86, 1.70], fibrinogen 1.02 fold-rise [95% CI: 0.98, 1.06], or D-dimer 1.02 fold-rise [95% CI: 0.88, 1.17] in individuals with CVD. One-day lagged analyses in the CVD subgroup found similar null results. These same models found no change in these blood markers at the same-day or 1-day lag in the group without CVD. In 21 individuals with CVD, a 10 mu g/m3 increase in same-day PM was associated with a 1.3 fold-rise [ 95% CI: 1.1, 1.7] in the level of monocyte chemoattractant protein-1. Conclusion: We did not find consistent effects of low ambient levels of PM on blood measures of inflammation or thrombosis in elderly individuals.