Ambient and microenvironmental particles and exhaled nitric oxide before and after a group bus trip.
OBJECTIVE
Airborne particles have been linked to pulmonary oxidative stress and inflammation. Because these effects may be particularly great for traffic-related particles, we examined associations between particle exposures and exhaled nitric oxide (FE(NO)) in a study of 44 senior citizens, which involved repeated trips aboard a diesel bus.


METHODS
Samples of FE(NO) collected before and after the trips were regressed against microenvironmental and ambient particle concentrations using mixed models controlling for subject, day, trip, vitamins, collection device, mold, pollen, room air nitric oxide, apparent temperature, and time to analysis. Although ambient concentrations were collected at a fixed location, continuous group-level personal samples characterized microenvironmental exposures throughout facility and trip periods.


RESULTS
In pre-trip samples, both microenvironmental and ambient exposures to fine particles were positively associated with FE(NO). For example, an interquartile increase of 4 microg/m(3) in the daily microenvironmental PM(2.5) concentration was associated with a 13% [95% confidence interval (CI), 2-24%) increase in FE(NO). After the trips, however, FE(NO) concentrations were associated pre-dominantly with microenvironmental exposures, with significant associations for concentrations measured throughout the whole day. Associations with exposures during the trip also were strong and statistically significant with a 24% (95% CI, 15-34%) increase in FE(NO) predicted per interquartile increase of 9 microg/m(3) in PM(2.5). Although pre-trip findings were generally robust, our post-trip findings were sensitive to several influential days.


CONCLUSIONS
Fine particle exposures resulted in increased levels of FE(NO) in elderly adults, suggestive of increased airway inflammation. These associations were best assessed by microenvironmental exposure measurements during periods of high personal particle exposures.
Adar
Sara Dubowsky
SD
Department of Environmental and Occupational Health Sciences, University of Washington, 4225 Roosevelt Way NE, Seattle, WA 98105, USA. dubowsky@u.washington.edu
Adamkiewicz
Gary
G
Gold
Diane R
DR
Schwartz
Joel
J
Coull
Brent A
BA
Suh
Helen
H
D000367:Age Factors; D000368:Aged; D001944:Breath Tests; D004781:Environmental Exposure; D005260:Female; D006801:Humans; D007249:Inflammation; D008171:Lung Diseases; D008297:Male; D008875:Middle Aged; D009569:Nitric Oxide / Q000032:analysis*; D010316:Particle Size; D014195:Travel; D001335:Vehicle Emissions
D001335:Vehicle Emissions; D009569:Nitric Oxide