Association between On-Road Particulate Matter Mixtures and Acute Cardiorespiratory Response in a Commuters Panel Study

摘要

BACKGROUND: We conducted the Atlanta Commuters Exposures studies to examine the hypothesis that exposures to traffic pollution mixtures occurring during rush hour car commuting lead to acute changes in cardiorespiratory response. METHODS: We recruited 100 adults to conduct two 2-hour scripted highway commutes during rush hour in Atlanta. A suite of in-vehicle particulate components were measured in the subjects' private vehicles. Health measurements were conducted before and immediately after the commutes and in 3 hourly intervals after commutes. Factor analysis of the particle species was conducted using a varimax rotation method to organize all PM components into co-varying groups. Associations between exposures and response were examined using mixed-effects linear regression analyses. RESULTS: Results indicate that in-cabin particles derive primarily from 3 processes: the resuspension of road dust containing crustal elements and previously-deposited brake pad residue with a contribution of normal fuel combustion; incomplete combustion processes producing PAHs and carbon particles; and non-deposited particles ablated from brake pads. Exhaled nitric oxide (eNO) levels, an indicator of upper airway inflammation, were significantly elevated after commuting ranging from 8.3 -13.7% higher than baseline levels (p ＜ 0.001) at each of measurement period. Positive associations existed between in-vehicle iron (Fe) concentrations, predominant within the crustal factor, and eNO measured following the commutes (IQR increase in Fe = 4.2% increase in eNO post commute [95% CI: 0.3 - 8.3 %]). CONCLUSIONS: While commuting, individuals are cumulatively exposed to elevated particulate and gaseous chemical pollution, noise, and psychosocial stress. The current results suggest that the development of novel exposure metrics that better reflect the multiplicity of exposures occurring during typical commuting may serve as more sensitive indicators of biological response.