Previously, with the continuous foggy weather in many parts of the country, “PM2.5” has become the hottest word in popular science. The main reason for the “explosion” of the PM2.5 value this time is the large emissions of sulfur dioxide, nitrogen oxides and dust caused by coal burning. Raws li ib qho ntawm cov cuab yeej tam sim no ntawm PM2.5 Kev qias neeg, cov pa paug pa roj hmab emissions ntawm cov roj tua hluav taws yog qhov tseem ceeb. Among them, sulfur dioxide accounts for 44%, nitrogen oxides account for 30%, and industrial dust and smoke dust together account for 26%. The treatment of PM2.5 is mainly industrial desulfurization and denitrification. On the one hand, the gas itself will pollute the atmosphere, and on the other hand, the aerosol formed by nitrogen oxides is an important source of PM2.5.