What caused the smog weather in many places in China?

Hazy weather is caused by a lot of dust on the ground and low air humidity. People and vehicles on the ground stir up dust. It may also be that automobile exhaust is the main pollutant emission. In recent years, there are more and more cars in cities, and the exhaust gas emitted by cars is a factor of smog. We should travel with low carbon, drive less and not drive. Reduce coal burning, strengthen afforestation, and chemical plants emit less polluting gases. For the sake of environmental protection, we hope everyone will take action to protect the earth and prevent smog weather. Puwei core meets the highest standards of American medical masks, and has good filterability, which not only prevents particles but also prevents droplets. The filtration efficiency is 99.8% for particles as small as 0. 1 micron, and 99.9% for bacteria or virus carriers as small as 0.3 micron (common in droplets). SecureFit patented technology is adopted to adapt to different face shapes and achieve a high degree of fit. At the same time, the six-point support disperses the pressure, and there is no ligature mark on the face, which is very comfortable to wear. That is, the price is not very close to the people, one is in 29 yuan ... in Tmall.