title: Exhaled nitric oxide in children with asthma and short-term PM2.5 exposure in Seattle.
abstract: The objective of this study was to evaluate associations between short-term (hourly) exposures to particulate matter with aerodynamic diameters < 2.5 microm (PM2.5) and the fractional concentration of nitric oxide in exhaled breath (FE(NO) in children with asthma participating in an intensive panel study in Seattle, Washington. The exposure data were collected with tapered element oscillation microbalance (TEOM) PM2.5 monitors operated by the local air agency at three sites in the Seattle area. FE(NO) is a marker of airway inflammation and is elevated in individuals with asthma. Previously, we reported that offline measurements of FE(NO) are associated with 24-hr average PM2.5 in a panel of 19 children with asthma in Seattle. In the present study using the same children, we used a polynomial distributed lag model to assess the association between hourly lags in PM2.5 exposure and FE(NO) levels. Our model controlled for age, ambient NO levels, temperature, relative humidity, and modification by use of inhaled corticosteroids. We found that FE(NO) was associated with hourly averages of PM2.5 up to 10-12 hr after exposure. The sum of the coefficients for the lag times associated with PM2.5 in the distributed lag model was 7.0 ppm FE(NO). The single-lag-model FE(NO) effect was 6.9 [95% confidence interval (CI), 3.4 to 10.6 ppb] for a 1-hr lag, 6.3 (95% CI, 2.6 to 9.9 ppb ) for a 4-hr lag, and 0.5 (95% CI, -1.1 to 2.1 ppb) for an 8-hr lag. These data provide new information concerning the lag structure between PM2.5 exposure and a respiratory health outcome in children with asthma.
authors.affiliation: Department of Environmental Health and Occupational Sciences, University of Washington, Seattle, Washington 98195-7234, USA.
authors.forename: Therese F
authors.initials: TF
authors.lastname: Mar
authors.forename: Karen
authors.initials: K
authors.lastname: Jansen
authors.forename: Kristen
authors.initials: K
authors.lastname: Shepherd
authors.forename: Thomas
authors.initials: T
authors.lastname: Lumley
authors.forename: Timothy V
authors.initials: TV
authors.lastname: Larson
authors.forename: Jane Q
authors.initials: JQ
authors.lastname: Koenig
mesh_terms: D000367:Age Factors; D000393:Air Pollutants / Q000032:analysis / Q000633:toxicity*; D001249:Asthma / Q000503:physiopathology*; D001944:Breath Tests; D002648:Child; D004781:Environmental Exposure; D006801:Humans; D006813:Humidity; D007249:Inflammation / Q000139:chemically induced; D015233:Models, Statistical; D009569:Nitric Oxide / Q000032:analysis*; D010316:Particle Size; D012137:Respiratory System / Q000473:pathology*; D013696:Temperature; D013997:Time Factors; D014861:Washington
chemical_list: D000393:Air Pollutants; D009569:Nitric Oxide