Comparison between several indices of exposure to traffic-related air pollution and their respiratory health impact in adults

¹ Epidemiology Dept. Local Health Unit ASL Roma E, Rome, Italy

^* To whom correspondence should be addressed. E-mail: cesaroni{at}asplazio.it.

Accepted 10 January 2008

	Abstract

Objective: To evaluate the association of different indices of traffic-related air pollution (self-report of traffic intensity, distance from busy roads from geographical information system (GIS), area-based emissions of particulate matter (PM), and estimated concentrations of nitrogen dioxide (NO2) from a land-use regression model) with respiratory health in adults.

Methods: A sample of 9,488 25-59 year-old Rome residents completed a self-administered questionnaire on respiratory health and various risk factors, including education, occupation, housing conditions, smoking, and traffic intensity in their area of residence. We used GIS to calculate the distance between their home address and the closest high-traffic road. For each subject, PM emissions in the area of residence as well as estimated nitrogen dioxide (NO2) concentrations as assessed by a land-use regression model (R2 value=0.69) were available. We used generalised estimating equations (GEE) to analyse the association between air pollution measures and prevalence of "ever" chronic bronchitis, asthma, and rhinitis taking into account the effects of age, gender, education, smoking habits, socioeconomic position, and the correlation of variables for members of the same family.

Results 397 subjects (4% of the study population) reported chronic bronchitis, 472 (5%) asthma, and 1227 (13%) rhinitis. Fifteen percent of subjects reported living in high traffic areas, 11% lived within 50m of a high traffic road, and 28% in areas with estimated NO2 greater than 50 µg/m3. Prevalence of asthma was associated only with self-reported traffic intensity whereas no association was found for the other more objective indices. Rhinitis, on the other hand, was strongly associated with all traffic-related indicators (e.g. OR=1.13, 95%CI:1.04-1.22 for 10 µg/m3 NO2), especially among non-smokers.

Conclusions: Indices of exposure to traffic-related air pollution are consistently associated with an increased risk of rhinitis in adults, especially among non-smokers. The results for asthma are weak, possibly due to ascertainment problems.

Keywords: Air pollution, adults, asthma, rhinitis, traffic