World Health Organization (WHO):
The World Health Organization (WHO) considers that PM2.5 less than 10 is a safe value; The World Health Organization also pointed out in the 2005 edition of the Air Quality Guide that when the average annual concentration of PM2.5 reaches 35 μ g/m3, compared with the situation of 10 μ g/m3, the risk of human death will increase by about 15%.
National standards:
The current standard in the United States is 35 micrograms per cubic meter, and the air quality index corresponding to PM2.5 is 100, which means that above 35 is not up to standard.
The current domestic standard is that the air quality index of PM2.5 with a concentration of 75 μ g/m3 is 100, that is, if it is higher than 75, it will not meet the standard.
Actual:
The 24-hour average value of PM2.5 concentration in the air from June 19 to June 20 in Beijing is
179 μ g/m3 (US data), 126 μ g/m3 (China data).