title: Pulmonary effects of indoor- and outdoor-generated particles in children with asthma.
abstract: Most particulate matter (PM) health effects studies use outdoor (ambient) PM as a surrogate for personal exposure. However, people spend most of their time indoors exposed to a combination of indoor-generated particles and ambient particles that have infiltrated. Thus, it is important to investigate the differential health effects of indoor- and ambient-generated particles. We combined our recently adapted recursive model and a predictive model for estimating infiltration efficiency to separate personal exposure (E) to PM2.5 (PM with aerodynamic diameter < or = 2.5 microm) into its indoor-generated (Eig) and ambient-generated (Eag) components for 19 children with asthma. We then compared Eig and Eag to changes in exhaled nitric oxide (eNO), a marker of airway inflammation. Based on the recursive model with a sample size of eight children, Eag was marginally associated with increases in eNO [5.6 ppb per 10-microg/m3 increase in PM2.5; 95% confidence interval (CI), -0.6 to 11.9; p = 0.08]. Eig was not associated with eNO (-0.19 ppb change per 10 microg/m3). Our predictive model allowed us to estimate Eag and Eig for all 19 children. For those combined estimates, only Eag was significantly associated with an increase in eNO (Eag: 5.0 ppb per 10-microg/m3 increase in PM2.5; 95% CI, 0.3 to 9.7; p = 0.04; Eig: 3.3 ppb per 10-microg/m3 increase in PM2.5; 95% CI, -1.1 to 7.7; p = 0.15). Effects were seen only in children who were not using corticosteroid therapy. We conclude that the ambient-generated component of PM2.5 exposure is consistently associated with increases in eNO and the indoor-generated component is less strongly associated with eNO.
authors.affiliation: Department of Environmental Health and Occupational Sciences, University of Washington, Seattle, Washington 98195, USA. jkoenig@u.washington.edu
authors.forename: Jane Q
authors.initials: JQ
authors.lastname: Koenig
authors.forename: Therese F
authors.initials: TF
authors.lastname: Mar
authors.forename: Ryan W
authors.initials: RW
authors.lastname: Allen
authors.forename: Karen
authors.initials: K
authors.lastname: Jansen
authors.forename: Thomas
authors.initials: T
authors.lastname: Lumley
authors.forename: Jeffrey H
authors.initials: JH
authors.lastname: Sullivan
authors.forename: Carol A
authors.initials: CA
authors.lastname: Trenga
authors.forename: Timothy
authors.initials: T
authors.lastname: Larson
authors.forename: L-Jane S
authors.initials: LJ
authors.lastname: Liu
mesh_terms: D000293:Adolescent; D000305:Adrenal Cortex Hormones; D000393:Air Pollutants / Q000009:adverse effects* / Q000032:analysis; D016902:Air Pollution, Indoor / Q000009:adverse effects* / Q000032:analysis; D001249:Asthma / Q000453:epidemiology*; D002648:Child; D015331:Cohort Studies; D004391:Dust / Q000032:analysis; D006798:Housing; D006801:Humans; D019570:Inhalation Exposure; D008962:Models, Theoretical; D009569:Nitric Oxide / Q000032:analysis*; D010316:Particle Size; D013147:Spirometry; D014861:Washington / Q000453:epidemiology
chemical_list: D000305:Adrenal Cortex Hormones; D000393:Air Pollutants; D004391:Dust; D009569:Nitric Oxide