According to the specific situation in China, the standard in China is 75. This is the highest line of international standards.
The larger this value is, the more dust (less than 2.5 microns in diameter) is contained in the air.
PM2.5 dust can carry many germs and viruses and enter the blood through lung cells. This is the harm.
Compared with atmospheric coarse particles, PM2.5 has the advantages of small particle size, large area, strong activity and easy attachment of toxic and harmful substances (such as heavy metals and microorganisms). ), it stays in the atmosphere for a long time and has a long transportation distance, so it has a great impact on human health and atmospheric environmental quality.
Extended data:
PM2.5 can be converted from oxides of sulfur and nitrogen. These gaseous pollutants are usually caused by human burning fossil fuels (coal, oil, etc.). ) and garbage. In developing countries, burning coal is the main way of household heating and energy supply. Diesel vehicles without advanced exhaust gas treatment devices are also sources of particulate matter. Impurities in diesel truck emissions will lead to more particulate matter.
Although fine particles are only a few components in the earth's atmosphere, they have an important impact on air quality and visibility. Compared with atmospheric coarse particles, fine particles are small in particle size, rich in a large number of toxic and harmful substances, stay in the atmosphere for a long time and have a long transportation distance.
Therefore, it has a great impact on human health and atmospheric environmental quality. Research shows that the smaller the particles, the greater the harm to human health. Fine particles can float far away, so the influence range is large.
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