A Study on Ambient Air Pollution and Hospital Visits of Patients in Tertiary Hospital at North Chennai – An Observational Study

Abstract

BACKGROUND: Air pollution is an important environmental risk factor for human health. Evidence is mounting that ambient air pollution exposure is signicantly associated with respiratory diseases. Ambient air pollution, such as nitrogen dioxide (NO2), sulfur dioxide (SO2), and particulate matter (PM), is associated with mortality and morbidity induced by respiratory diseases. The relationship between air pollutants and respiratory hospital admissions has been reported both in developed countries and in developing countries. Other studies have shown an adverse effect of ambient air pollution exposure on morbidity and mortality, as well as on healthcare costs. AIM OF THE STUDY: To investigate the association between ambient air pollutant exposure and daily hospital admissions for respiratory diseases in both childrens and Adults. METHODOLOGY: The daily emergency hospital admissions for respiratory conditions in the north part of Chennai during 2019- 2020 were recorded. Daily counts of hospital admissions for total respiratory conditions (43 admissions day(-1)), acute respiratory infections including pneumonia (18 day(-1)), chronic obstructive pulmonary disease (COPD) (13 day(-1)), and asthma (4.5 day(-1)) among residents of all ages and among children (0-14 yrs) were analysed. The generalized additive models included spline smooth functions of the day of study, mean temperature, mean humidity, inuenza epidemics, and indicator variables for days of the week and holidays. Total respiratory admissions were signicantly associated with the same-day level of NO2 (2.5% increase per interquartile range (IQR) change, 22.3 microg x m(-3)) and CO (2.8% increase per IQR, 1.5 mg x m(-3)). RESULTS: The daily mean concentrations of pollutants across all studies were 65.2 µg/m3 for PM10, 45.8 µg/m3 for PM2.5, 27.7 µg/m3 for SO2, 35.0 µg/m3 forNO2and1698µg/m3for CO, and 81.1µg/m3for O3. For the single variable models, the linear effect of PM10, PM2.5, and PM1 was evaluated by adjusting for the inuence of temperature. The association between hospital admissions for respiratory disease and the level of particulate matter was statistically signicant at 0-3 daylag in females and overall. In males, no statistically signicant effect was found at lag 3 for PM10 or at lag2-3 for PM2.5 and PM1.The associations between PM2.5 and PM1, and risk of admission were no longer signicant at some lags after adjusting for NO2, SO2, CO, and O3 separately. No associations were found at lag 3 after adjusting for NO2 or at lag 2 and 3 after adjusting for O3. The effects of PM2.5 and PM1 were not changed after adjusting for CO but were weaker after adjusting for other air pollutants (NO2, SO2,and O3). CONCLUSION: The ndings of this study demonstrated that O3 was associated with an increased risk of respiratory-related admissions, especially for children <5years old. The effect was stronger in the winter than in the summer with each increase of 10 µg/m3 of O3 in winter, the risk of admissions for respiratory diseases after 5 days of exposure increased by 6.2% (95% CI3.7% - 8.8%). No signicant association between O3 and hospital admissions for wheeze-associated disorders specically was observed in children.