Effect of outdoor air pollution on respiratory deseases in the District of Tunis

Abstract

Abstract Background Asthma and Chronic Obstructive Pulmonary Disease (COPD) are the two most common chronic obstructive pulmonary diseases worldwide. The objective of this study was to analyze the relation between the daily levels of air pollution indicators and the number of emergency department visits (EDV) for asthma and COPD exacerbation in the District of Tunis. Methods We conducted a retrospective ecological study. We collected daily morbidity data from the emergency register of Ariana Mami Hospital from 1 January 2007 to 31 December 2014. We investigated the association between daily EDV for asthma or COPD exacerbation and daily concentrations levels of air pollutants by simple Pearson correlation and by binomial negative regression using generalized linear models (GLM). Results For morbidity data, we recorded 19127 EDV for asthma (10771, 56.3%) and COPD exacerbation (8356, 43.7%) between 2007 and 2014. We observed a rising trend in the number of EDV for COPD since 2007 with winter seasonality. Regarding the profile of air pollution in the study region, we have exceeded the thresholds of all standards for PM10, exceeding the Canadian standard for O3. However, no threshold exceeded for NO2 and SO2. In the univariate analysis, there was a positive correlation between the daily number of EDV for asthma and COPD exacerbation and NO2 ambient concentration (r = 0.121, p < 10-3) and O3 level (r = 0.066, P < 10-3). Multivariate analysis showed a significant positive association between the daily number of EDV for asthma and COPD exacerbation and NO2 daily concentration (Adjusted OR = 1.033, CI = [1.011 - 1.055], P < 10-3) with a delayed effect of 10 days for NO2 and 12 days for O3. Conclusions The exacerbation of asthma and COPD was correlated to the NO2 outdoor air concentration level, with an immediate and other delayed effect of 10 days, also with the 12-day lag from the elevation of O3. Key messages Ambient air pollution is a major risk factor for respiratory health. Reducing NO2 emissions could decrease morbidity and direct health care costs of respiratory diseases.