Background and objectives: Exposure to particulate matter (PM2.5) has been associated with increased cardiovascular outcomes, mediated by a hypothesized biological mechanism of systemic inflammation and oxidation. Although PM10 has been linked to inflammatory markers in a nationally representative sample (NHANES) using data from earlier cycles (1989-1994); no study has considered these relationships for PM2.5 in more recent time periods. We examined the association of ambient PM2.5 exposure and inflammatory markers in adult NHANES participants for cycles 2001-2008.
Methods: We linked each of the adult NHANES participant's address with meteorological and modeled air pollution data for each census tract in conterminous United States. The effects of short and long term PM2.5 on C-reactive protein, white blood cells, fibrinogen and homocysteine were analyzed using multiple linear regression, adjusting for cardiovascular risk factors, temperature and ozone. SAS SURVEYREG was used to account for the complex survey design of NHANES.
Results: In the overall population, no significant positive associations were noted for either short or long term PM2.5 exposures for any of the biomarkers after controlling for confounders. However, stronger associations were found among obese, diabetics, hypertensive and smokers. For every 10μg/m(3) increase in PM2.5, there was an increase of (a) 36.9% (95% CI: 0.1%, 87.2%) in CRP at annual average PM2.5 (adjusting for short term exposure) among diabetics (b) 2.6% (95% CI: 0.1%, 5.1%) in homocysteine at lag 0 among smokers.
Conclusions: In a nationally representative sample of individuals we noted no overall association between PM2.5 and biomarkers of cardiovascular risk. However, sensitive subgroups manifested increases in these markers to PM2.5 exposure. Further studies should concentrate on the impact of PM2.5 on these biomarkers in those with multiple cardiovascular risk factors.
Keywords: Air pollution; Biomarkers; Cardiovascular disease; PM2.5.
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