title: Coarse particles and respiratory emergency department visits in California.
abstract: Although respiratory disease has been strongly connected to fine particulate air pollution (particulate matter <2.5 μm in diameter (PM2.5)), evidence has been mixed regarding the effects of coarse particles (particulate matter from 2.5 to 10 μm in diameter), possibly because of the greater spatial heterogeneity of coarse particles. In this study, we evaluated the relationship between coarse particles and respiratory emergency department visits, including common subdiagnoses, from 2005 to 2008 in 35 California counties. A time-stratified case-crossover design was used to help control for time-invariant confounders and seasonal influences, and the study population was limited to those residing within 20 km of pollution monitors to mitigate the influence of spatial heterogeneity. Significant associations between respiratory emergency department visits and coarse particle levels were observed. Asthma visits showed associations (for 2-day lag, excess risk per 10 μg/m³ = 3.3%, 95% confidence interval: 2.0, 4.6) that were robust to adjustment by other common air pollutants (particles <2.5 μm in diameter, ozone, nitrogen dioxide, carbon monoxide, and sulfur dioxide). Pneumonia and acute respiratory infection visits were not associated, although some suggestion of a relationship with chronic obstructive pulmonary disease visits was present. Our results indicate that coarse particle exposure may trigger asthma exacerbations requiring emergency care, and reducing exposures among asthmatic persons may provide benefits.
authors.affiliation: brian.malig@oehha.ca.gov
authors.forename: Brian J
authors.initials: BJ
authors.lastname: Malig
authors.forename: Shelley
authors.initials: S
authors.lastname: Green
authors.forename: Rupa
authors.initials: R
authors.lastname: Basu
authors.forename: Rachel
authors.initials: R
authors.lastname: Broadwin
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000393:Air Pollutants / Q000009:adverse effects; D002140:California / Q000453:epidemiology; D002648:Child; D002675:Child, Preschool; D004636:Emergency Service, Hospital / Q000706:statistics & numerical data*; D005260:Female; D006801:Humans; D007223:Infant; D008297:Male; D008875:Middle Aged; D052638:Particulate Matter / Q000009:adverse effects*; D029424:Pulmonary Disease, Chronic Obstructive / Q000453:epidemiology / Q000209:etiology; D012140:Respiratory Tract Diseases / Q000453:epidemiology* / Q000209:etiology; D014887:Weather; D055815:Young Adult
chemical_list: D000393:Air Pollutants; D052638:Particulate Matter
keywords: air pollution; asthma; case-crossover; emergency medical services; hospitalization; particulate matter; respiratory tract diseases