Assessment of intra-urban variability in outdoor air quality and its health risks.

Ambient air quality along with micrometeorological data was measured in a suburban area of India, from March 2006 to February 2007 in order to assess the intra-urban variability of air pollutants in different parts of the city. The prevalences of asthma and respiratory disorders were determined using a questionnaire survey of 750 adults. The association between intra-urban variability of air pollution and respiratory diseases were evaluated with logistic regression analyses. Compared with subjects staying 5.0 km away from a main road to those subjects living within 0.5 km and 1.0 km had odds ratios of 1.00 (95% CI, 0.85 to 1.50), 3.57 (95% CI, 3.00 to 3.95), and 3.00 (95% CI, 2.85 to 3.50), respectively for doctor-diagnosed asthma. A reduction of measured pollutant concentration with increase in distance from the main road was observed. The study demonstrated that residential exposure to highly trafficked roads is associated with respiratory diseases. Considering the continuing rise in motorized vehicle use and the paramount role of inhalation toxicology, these findings have high public health relevance and should be corroborated in prospective studies.