Analysis of the Air Pollution Index and Meteorological Factors and Risk Assessment for Tibet

An analysis and statistical evaluation of the environmental air quality, meteorological conditions, and human health effects were carried out for major cities and towns in Tibet. The study selected PM 10 , SO 2 , NO 2 , PM 2.5 , O 3 , and CO atmospheric pollutant monitoring data, a pollutant index, and the air quality index for seven cities and towns in Tibet in the year 2017 and for the Lhasa urban area in the period from June 2000 to December 2017. The data were combined with meteorological elements, namely precipitation, temperature, wind, and total solar radiation, for the same period. Results show that the air quality index is highest in Nag Qu, among of the seven cities and towns, followed by Shigatse, which roughly reflects the characteristics of pollution emissions dominated by biomass fuels in agricultural and pastoral areas of Tibet, a lack of vegetation, strong winds and less rain, and increased particle concentration. These factors affects human health. The six pollutants had higher concentrations in the winter half of the year (November to April) and lower concentrations in the summer half of the year (May to October); i.e., the concentration of pollutants was 38% higher in the winter half of the year. The change trend of the six pollutants has changed over the years; the concentrations of NO 2 and PM 2.5 have increased, the concentration of PM 10 has decreased, and the concentrations of O 3 and SO 2 have not changed appreciably. According to national air quality standards, the percentage number of days with excellent air quality was 22.7%, the percentage number of days with good air quality was 62.7%, the percentage number of days with light pollution was 11.3%, and the percentage number of days with moderate or heavy pollution was 0.6%. Meteorological factors such as precipitation, wind speed, visibility, and total solar radiation affect air pollution.