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Residential exposure to motor vehicle emissions and the risk of wheezing among 7-8 year-old schoolchildren: a city-wide cross-sectional study in Nicosia, Cyprus

Nicos Middleton1*, Panayiotis Yiallouros2, Nicolaos Nicolaou3, Savvas Kleanthous4, Spiros Pipis2, Maria Zeniou2, Philip Demokritou5 and Petros Koutrakis5

Author Affiliations

1 Department of Nursing, School of Health Sciences, Cyprus University of Technology, Nicosia, Cyprus

2 Cyprus International Institute for the Environment and Public Health in association with Harvard School Public Health, Cyprus University of Technology, Limassol, Cyprus

3 Respiratory Research Group, School of Translational Medicine, Wythenshawe Hospital, Manchester, UK

4 Air Quality Section, Department of Labor Inspection, Nicosia, Cyprus

5 Department of Environmental Health, Exposure, Epidemiology & Risk Program, Harvard School of Public Health, Boston MA 02215, USA

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Environmental Health 2010, 9:28  doi:10.1186/1476-069X-9-28

Published: 18 June 2010

Abstract

Background

Several studies have reported associations between respiratory outcomes in children and a range of self-reported, administrative or geographical indicators of traffic pollution. First-time investigation into the frequency of asthmatic symptoms among 7-8 year-old Cypriot children in 1999-2000 showed increased prevalence in the capital Nicosia compared to other areas. Geographical differences on an island the size of Cyprus may reflect environmental and/or lifestyle factors. This study investigates the relationship between self-reported symptoms and residential exposure to motor vehicle emissions among Nicosia schoolchildren.

Methods

The addresses of children in the metropolitan area of Nicosia who participated in the original survey (N = 1,735) were geo-coded and the level of exposure of each child was assessed using distance- and emission-based indicators (i.e. estimated levels of particulate matter and nitrogen oxides emissions due to motor vehicles on main roads around the residence). Odds ratios of wheezing and asthma diagnosis in relation to levels of exposure were estimated in logistic regression models adjusting for person-based factors, co-morbidity and intra-school clustering.

Results

We found an increased risk of wheezing at distances less than 50 m from a main road and/or only among those experiencing the highest levels of exposure. The strongest effect estimates were observed when exposure was defined in terms of the cumulative burden at all roads around the residence. Adjusted odds ratios for current wheezing were 2.33 (95% CI 1.27, 4.30) amongst the quartile of participants exposed to the highest levels of PM at all roads 50 m of their residence and 2.14 (95% CI 1.05, 4.35) for NOx, with no effect at intermediate levels of exposure. While the direction of effect was apparent at longer distances, differences were generally not statistically significant.

Conclusions

Children experiencing the highest burden of emissions in Nicosia seem to be at a higher risk of reporting asthmatic symptoms. Due to the small number of children residing at close proximity to main roads and lack of evidence of risk at intermediate levels of exposure or longer distances, the observed pattern alone does not explain the generally higher prevalence observed in urban Nicosia compared to other areas.