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Robert Dales,^1,2 Amanda Wheeler,³ Mamun Mahmud,⁴ Anna Maria Frescura,⁵ Marc Smith-Doiron,⁴ Elizabeth Nethery,³ and Ling Liu⁴

¹Faculty of Medicine, University of Ottawa, Ottawa Hospital Research Institute, Ottawa, Ontario, Canada; ²Health Canada, Ottawa, Ontario, Canada; ³Air Health Science Division, Water, Air, and Climate Change Bureau, Ottawa, Ontario, Canada; ⁴Biostatistics and Epidemiology Division, Environmental Health Science and Research Bureau, Health Canada, Ottawa, Ontario, Canada; ⁵Immunization and Respiratory Infections Division, Public Health Agency of Canada, Ottawa, Ontario, Canada

Abstract
Background: Living near major roadways has been associated with an increase in respiratory symptoms, but little is known about how this relates to airway inflammation.

Objective: We assessed the effects of living near local residential roadways based on objective indicators of ventilatory function and airway inflammation.

Methods: We estimated ambient air pollution, resolved to the level of the child's neighborhood, using a land-use regression model for children 9–11 years of age. We also summed the length of roadways found within a 200-m radius of each child's neighborhood. We had measurements of both air pollution exposure and spirometry for 2,328 children, and also had measurements of exhaled nitric oxide (eNO) for 1,613 of these children.

Results: Each kilometer of local roadway within a 200-m radius of the home was associated with a 6.8% increase in eNO (p = 0.045) . Each kilometer of any type of roadway (local, major, highway) was also associated with an increase in eNO of 10.1% (p = 0.002) . Each microgram per cubic meter increase in PM_2.5 was associated with a 3.9% increase in eNO (p = 0.058) and 0.70% decrease in forced vital capacity (FVC) expressed as a percentage of predicted (p = 0.39) . Associations between roadway density and both forced expired volume in 1 sec and FVC were negative but not statistically significant at p < 0.05.

Conclusion: Traffic from local neighborhood roadways may cause airway inflammation as indicated by eNO. This may be a more sensitive indicator of adverse air pollution effects than traditional measures of ventilatory function.

Key words: air pollution, environment, nitric oxide, respiratory system, spirometry. Environ Health Perspect 116:1423–1427 (2008) .  doi:10.1289/ehp.10943 available via http://dx.doi.org/ [Online 1 August 2008]

Address correspondence to R. Dales, The Ottawa Hospital (General Campus) , 501 Smyth Rd., Box 211, Ottawa, Ontario, Canada K1H 8L6. Telephone: (613) 737-8198. Fax: (613) 737-8537. E-mail: rdales@ohri.ca

We thank the Centre for Environmental Health of Ontario, the City of Windsor school boards, the Windsor Community parents and children, the Windsor Medical Officer of Health, the Essex County Health Unit, the University of Windsor, Environment Canada, and the Ministry of Environment of Ontario.

This research was funded by the Canada–U.S. International Joint Commission.

The authors declare they have no competing financial interests.

Received 3 October 2007 ; accepted 1 August 2008.