Spatiotemporal Variability of Air Quality Time Series for developing countries: Case of Ho Chi Minh city, Vietnam

In the recent years, air pollution has become a severe problem not only for Vietnam, but also for other countries. Ho Chi Minh City (HCMC) is the largest city in Vietnam where many air pollutants exceeded the Vietnam national technical regulation in ambient air quality including PM2.5, NOx, Ozone and CO. These high pollutant concentrations have destroyed human health of people in Ho Chi Minh City. This research is aimed to (i) analyse and assess the change in spatiotemporal of the air polluted substances in Ho Chi Minh City; (ii) study the impact of weather patern to air pollutants dispersion over Ho Chi Minh City. The description statistical method is applied to evaluate the air quality in every monitoring location during the period 2005 to 2016, and the Inverse Distance Weighting (IDW) spatial interpolation from Geographical Information Systems (GIS) was applied to create a map of polluted substances in air quality, especially Total Suspended Particles (TSP), Nitrogen oxides (NOx), Lead (Pb) and Carbon monoxide (CO), of the change in concentration of the polluted substances for every pixel in all researched locations. IDW method was validated by comparing between air quality monitoring and IDW spatial interpolation method. The results shown that IDW method is qualify for this study with R2 = 0.93 and d = 0.74 at Dinh Tien Hoang – Dien Bien Phu, An Suong and Go Vap monitoring locations. The IDW interpolation method was also good result for NOx with R2 = 0.96 and d = 0.75 at the Hang Xanh, An Suong, and Huynh Tan Phat monitoring locations. The results shown that the highest CO concentration is in Go Vap district, with the average is 14.849 mg/m3, TSP is highest in An Suong area with the average is 0.687mg/m3. NOx is highest in Dien Bien Phu wih 0.199 mg/m3. The spatial of air quality shown that the spread continues towards the north, northwest, and northeast direction of Ho Chi Minh City because the main air emission sources are in the center of HCMC and the main wind direction is south, southeast and northeast. The wind direction blows air pollutants from center of city toward to the north, northwest, and northeast of Ho Chi Minh City. The results of study also shown that the relations between policy and air pollution level. Policy interventions on air quality management will have a major impact on reducing air pollution for HCMC, such as policies that tighten vehicle exhaust emissions (from EURO II standard to EURO VI standard) and policy on cleaner fuel.