On December 30, the official Sina Weibo account of the Chinese Academy of Sciences (CAS) wrote a post introducing the results of their research into the chemical composition of Beijing’s PM2.5 particles of pollution. The top three sources of PM 2.5 are secondary inorganic aerosols (colloids of fine solid particles or liquid droplets in air that can be formed after release of a variety of pollutants), which makes up about 26% of total PM2.5; industrial pollution, which is about 25%, and the burning of coal, which comprises around 18%. Soil dust, biomass fuels, automobile exhaust and waste incineration are also major contributors. Interestingly, automobile exhaust, which is often said to be a great source of the air pollution earlier, only comprises less than 4% of the total PM2.5, according to the CAS stidy.
The research also found that dust from construction sites and re-suspended dust from streets are major sources of dust in autumn and winter, while industrial pollution is a bigger factor in the summer.
The results indicate that coal burning in Hebei province contributes the most to the hazy air in Beijing and Tianjin. Thus control of Beijing local air pollution calls for both the improvement of the energy structure and regional joint corporation.
However, soon after the report released, Pan Tao, president of the Beijing Municipal Research Institute of Environmental Protection, openly challenged the research results. By pointing out the self-contradictions of CAS’ research and citing studies done by other prestigious research institutes, Pan questioned the accuracy of the findings. Pan especially questioned the portion contributed by the motor vehicle emissions, which Pan insists is ‘undoubtedly’ the major source of Beijing’s air pollution.
The Party mouthpiece thePeople’s Daily previously published a different set of data for PM2.5 sources in November 2013. According to the earlier data set, in Beijing, motor vehicle emissions contributed about 22% of total PM2.5 pollutants while coal burning was responsible for about 17%.