Outdoor Air Pollution and Emergency Department Visits for Respiratory Illness in Greater Tunis District, between 2007 and 2010

Abstract

Background: Ambient air pollution contributes to the development and the exacerbation of respiratory illness. The aim of this work was to study the impact of the outdoor air pollution on the emergency department visits for asthma and chronic obstructive pulmonary disease (COPD) exacerbation. Methods: Morbidity data were collected from the emergency department register of the A Mami hospital, from January, 1st 2007 to December, 31th 2010. Information about age, sex and date of the emergency department visits were obtained for patients with the diagnosis of asthma or COPD. Concentration levels of NO2, SO2, O3, and particulate matter (PM10) were collected from the National Observatory of the air quality in Tunisia. The impact of the outdoor air pollution on the daily emergency department visits was studied by a simple Pearson correlation and by a binomial negative regression using generalized linear models. Results: We recorded 9814 visits to the emergency department for asthma (6499, 65.5%) or COPD exacerbation (3315, 34.5%) between 2007 and 2010. Overall mean age was 52±21 years; it was respectively 47±21 and 60±18 years for asthma and COPD. About 63% were male. Positive correlation was observed between number of visits for respiratory symptoms and NO2 ambient air concentration (Spearman correlation coefficient =0.204, p<10-3), and O3 level (Spearman correlation coefficient=0.109, p<10-3). Multivariate analysis showed significant positive association between the daily numbers of emergency department visits for asthma and COPD (Adjusted OR=1.011, 95% CI: 1.006-1.015, p<10-3). Conclusions: Exacerbation of respiratory illness in the Greater Tunis was correlated to the NO2 outdoor air concentration level which can be related to the traffic density in the capital city of Tunisia and its provinces.