The influence of living near roadways on spirometry and exhaled nitric oxide in elementary schoolchildren

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 PM2.5 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 I see 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.