What is the specific object of dust hygiene standard?

The hygienic standard of dust is based on floating dust.

First of all, the hygienic standard stipulates the maximum allowable concentration of harmful substances in the air of workshops and residential areas. For example, the maximum allowable concentration of general dust in workshop air is 10 mg/m3, and the maximum allowable concentration of dust containing more than free silica 10% is 2 mg/m3.

In addition, floating dust refers to the weather phenomenon that dust or soil particles are suspended in the atmosphere, making the horizontal visibility less than 10 km. ? [3]? Floating dust weather, that is, the lowest intensity sandstorm, is a weather phenomenon formed by the generation and transmission of long-distance sandstorms or local sand blowing weather. The strength is weakened, and after the coarse particles in the dust settle by gravity, the fine particles are continuously transported and float in the air. When the wind speed continues to decrease, the suspended dust particles will settle to the ground, so it is commonly known as "falling yellow sand".

In dusty weather, a large amount of fine sand floats in the air, resulting in serious air pollution. When the wind speed decreases, floating dust will fall to the ground, forming accumulated dust. If it rains at the same time, it will form "mud rain" It affects flowers and plants and worsens the surrounding environment. In dusty weather, people's eyes, nose, throat, skin and other direct contact parts will be damaged to a certain extent, mainly manifested as runny nose, tears, cough, expectoration and other irritating symptoms and allergic reactions, which can seriously lead to skin inflammation and conjunctivitis. Go out as little as possible in dusty weather, and close the doors and windows at home in time, especially for patients with chronic bronchitis and families of the elderly and children with relatively weak resistance.

This is also closely related to the recent air pollution, which is closely related to lung diseases. When the outdoor air quality is not good, it is not suitable to go out for direct contact activities, and protective measures should be taken. The following is a weather image of floating dust