| Ambient and Microenvironmental Particles and Exhaled Nitric Oxide Before and After a Group Bus Trip Sara Dubowsky Adar,1 Gary Adamkiewicz,2 Diane R. Gold,2,3 Joel Schwartz,2,3,4 Brent A. Coull,5 and Helen Suh2 1Department of Environmental and Occupational Health Sciences, University of Washington, Seattle, Washington, USA; 2Department of Environmental Health, Harvard School of Public Health, Boston, Massachusetts, USA; 3Channing Laboratory, Department of Medicine, Brigham and Women's Hospital, Boston, Massachusetts, USA; 4Department of Epidemiology, and 5Department of Biostatistics, Harvard School of Public Health, Boston, Massachusetts, USA Abstract
Objectives: 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 (FeNO) in a study of 44 senior citizens, which involved repeated trips aboard a diesel bus. Methods: Samples of FeNO 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 FeNO. For example, an interquartile increase of 4 µg/m3 in the daily microenvironmental PM2.5 concentration was associated with a 13% [95% confidence interval (CI) , 2–24%) increase in FeNO. After the trips, however, FeNO concentrations were associated predominantly 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 FeNO predicted per interquartile increase of 9 µg/m3 in PM2.5. 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 FeNO in elderly adults, suggestive of increased airway inflammation. These associations were best assessed by microenvironmental exposure measurements during periods of high personal particle exposures. Key words: air pollution, exhaled nitric oxide, inflammation, particulate matter, traffic. Environ Health Perspect 115:507–512 (2007) . doi:10.1289/ehp.9386 available via http://dx.doi.org/ [Online 4 December 2006]
Address correspondence to S.D. Adar, Department of Environmental and Occupational Health Sciences, University of Washington, 4225 Roosevelt Way NE, Suite 302, Box Number: 354965, Seattle, WA 98105-8123 USA. Telephone: (206) 221-5932. Fax: (206) 685-3872. E-mail: dubowsky@u.washington.edu We are grateful for the input of D. Dockery, A. Zanobetti, and E. Rimm and appreciate the vital contributions of M. Davey, J. Turner, S. Forrester, C. Peter, our field staff, and study subjects. This work was funded by the National Institute of Environmental Health Sciences (ES09825/ES00002) , U.S. Environmental Protection Agency (R827353) , and Electric Power Research Institute (EPRI) (W09207) . H.S. received grant support from EPRI but certifies that her freedom to design, conduct, interpret, and publish research is not compromised as a result of this sponsorship. The other authors declare they have no competing financial interests.
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