Chronic exposure to outdoor air pollution and diagnosed cardiovascular disease: meta-analysis of three large cross-sectional surveys.

BACKGROUND: Higher exposure to outdoor air pollution is associated with increased cardiopulmonary deaths, but there is limited evidence about the association between outdoor air pollution and diagnosed cardiovascular disease. Our study aimed to estimate the size of the association between long term exposure to outdoor air pollution and prevalent cardiovascular disease. METHODS: We carried out a cross-sectional analysis of data on more than 19,000 white adults aged 45 and older who participated in three representative surveys of the English population in 1994, 1998 and 2003, examining the relationship between self-reported doctor-diagnosed cardiovascular disease and exposure to outdoor air pollutants using multilevel regression techniques and meta-analysis. RESULTS: The combined estimates suggested that an increase of 1 microg m-3 in concentration of particulate matter less than 10 microns in diameter was associated with an increase of 2.9% (95% CI -0.6% to 6.5%) in prevalence of cardiovascular disease in men, and an increase of 1.6% (95%CI -2.1% to 5.5%) in women. The year-specific analyses showed strongly positive associations in 2003 between odds of cardiovascular disease in both men and women and exposure to particulate matter but not in 1994 or 1998. We found no consistent associations between exposure to gaseous air pollutants and doctor-diagnosed cardiovascular disease. CONCLUSION: The associations of prevalent cardiovascular disease with concentration of particulate matter less than 10 microns in diameter, while only weakly positive, were consistent with the effects reported in cohort studies. The results provide evidence of the size of the association between particulate air pollution and the prevalence of cardiovascular disease but no evidence for an association with gaseous pollutants. We found strongly positive associations between particulate matter and cardiovascular disease in 2003 only, which highlights the importance of replicating findings in more than one population.

Chronic exposure to outdoor air pollution and markers of systemic inflammation.

BACKGROUND: Cohort studies suggest that long-term exposure to higher levels of outdoor air pollution increases risk of developing cardiovascular disease. One suggested mechanism is that air pollution, especially particulate matter, induces systemic inflammation, thereby increasing the risk of developing long-term pathologic changes in the cardiovascular system, We aimed to examine the association between long-term exposure to higher levels of air pollution and chronic systemic inflammation. METHODS: We examined the relationship between 2 markers of systemic inflammation (fibrinogen and C-reactive protein) and measures of outdoor air pollution estimated for each postcode sector of residence, using models incorporating information on pollutant emissions from multiple sources, and atmospheric dispersion and processing, in 3 representative cross-sectional studies of the English population in 1994, 1998, and 2003. These included about 25,000 adults with fibrinogen measurements and 17,000 adults with C-reactive protein measurements. We used multilevel linear regression modeling and pooled the results from the 3 surveys using meta-analysis. RESULTS: We found no associations between concentrations of fibrinogen or C-reactive protein and measures of outdoor air pollution (particulate matter <10 mum in diameter (PM10), nitrogen dioxide, sulfur dioxide, and ozone). Specifically, we found, for each 1-microg/m(3) [corrected] increase in PM(10) concentration, a change in fibrinogen concentrations of -0.08% (95% confidence interval = -0.25 to [corrected] 0.10) and in C-reactive protein concentrations of 0.14% (-1.00 to [corrected] 1.30). CONCLUSIONS: Our findings do not support the hypothesis that the association between outdoor air pollution exposure and later cardiovascular disease is mediated by chronic systemic inflammation.