title: Associations between summertime ambient pollutants and respiratory morbidity in New York City: comparison of results using ambient concentrations versus predicted exposures.
abstract: Epidemiological analyses of air quality often estimate human exposure from ambient monitoring data, potentially leading to exposure misclassification and subsequent bias in estimated health risks. To investigate this, we conducted a case-crossover study of summertime ambient ozone and fine particulate matter (PM(2.5)) levels and daily respiratory hospitalizations in New York City during 2001-2005. Comparisons were made between associations estimated using two pollutant exposure metrics: observed concentrations and predicted exposures from the EPA's Stochastic Human Exposure and Dose Simulation (SHEDS) model. Small, positive associations between interquartile range mean ozone concentrations and hospitalizations were observed and were strongest for 0-day lags (hazard ratio (HR)=1.013, 95% confidence interval (CI): 0.998, 1.029) and 3-day lags (HR=1.006, 95% CI: 0.991, 1.021); applying mean predicted ozone exposures yielded similar results. PM(2.5) was also associated with admissions, strongest at 2- and 4-day lags, with few differences between exposure metrics. Subgroup analyses support recognized sociodemographic differences in concentration-related hospitalization risk, whereas few inter-stratum variations were observed in relation to SHEDS exposures. Predicted exposures for these spatially homogenous pollutants were similar across sociodemographic strata, therefore SHEDS predictions coupled with the case-crossover design may have masked observable heterogeneity in risks. However, significant effect modification was found for subjects in the top exposure-to-concentration ratio tertiles, suggesting risks may increase as a consequence of infiltration or greater exposure to outdoor air.
authors: 1] New York State Department of Health, Center for Environmental Health, Empire State Plaza, Albany, New York, USA [2] Department of Epidemiology and Biostatistics, School of Public Health, University at Albany, SUNY, Rensselaer, New York, USA.
authors: Rena R
authors: RR
authors: Jones
authors: Halûk
authors: H
authors: Özkaynak
authors: Seema G
authors: SG
authors: Nayak
authors: Valerie
authors: V
authors: Garcia
authors: Syni-An
authors: SA
authors: Hwang
authors: Shao
authors: S
authors: Lin
mesh_terms: D000393:Air Pollutants / Q000633:toxicity*; D004781:Environmental Exposure; D006801:Humans; D009519:New York City; D012137:Respiratory System / Q000187:drug effects*
chemical_list: D000393:Air Pollutants