Air pollution and risk of respiratory and cardiovascular hospitalizations in the most populous city in Vietnam

Dung Phung, To Thi Hien, Ho Nhut Linh, Ly M.T. Luong, Lidia Morawska, Cordia Chu, Nguyen Duy Binh, Phong K. Thai

Air pollution has become an alarming issue in Vietnam recently; however, there was only one study so far on the effects of ambient air pollution on population health. Our study aimed to investigate the short-term effects of air pollutants including PM10, NO2, SO2, and O3 on respiratory and cardiovascular hospitalizations in Ho Chi Minh City (HCMC), the largest city in Vietnam. Data on hospitalization from the two largest hospitals in HCMC and daily records of PM10, NO2, SO2, O3 and meteorological data were collected from February 2004 to December 2007. A time-series regression analysis with distributed lag model was applied for data analysis. Changes in levels of NO2 and PM10 were strongly associated with hospital admissions for both respiratory and cardiovascular diseases (CVD); whereas levels of SO2 were only moderately associated with respiratory and CVD hospital admissions and O3 concentration was not associated with any of them. For a 10μg/m(3) increase of each air pollutant, the risk of respiratory admissions increased from 0.7% to 8% while the risk of CVD admissions increased from 0.5% to 4%. Females were found to be more sensitive than males to exposure to air pollutants in regard to respiratory diseases. In regard to CVD, females (RR, 1.04, 95% CI, 1.01-1.07) had a slightly higher risk of admissions than males (RR, 1.03, 95% CI, 1-1.06) to exposure to NO2. In contrast, males (RR, 1.007, 95%CI, 1-1.01) had a higher risk of admission than females (RR, 1.004, 95%CI, 1.001-1.007) to exposure to PM10. People in the age group of 5-65year-olds had a slightly higher risk of admissions caused by air pollutants than the elderly (65+years old) except for a significant effect of PM10 on the risk of cardiovascular admissions was found for the elderly only.