What do PM2.5 and PM 10 mean?

1. Definition: PM2.5 refers to particles with aerodynamic equivalent diameter less than or equal to 2.5 microns in ambient air, also known as fine particles and particles that can enter the lungs.

2. Features:

Its diameter is less than 1/20 of the thickness of human hair, and it can be suspended in the air for a long time. The higher its content (concentration) in the air, the more serious air pollution. Although PM2.5 is only a small part of the composition of the earth's atmosphere, it has an important impact on air quality and visibility.

PM2.5 has the advantages of small particle size, large specific surface area, strong activity, easy attachment of toxic and harmful substances (such as heavy metals and microorganisms), long residence time in the atmosphere and long transportation distance, so it has a great impact on human health and atmospheric environmental quality.

Ii. PM 10

1, definition: PM 10 is inhalable particulate matter with aerodynamic equivalent diameter less than or equal to 10 micron, which refers to the general term of solid and liquid particulate matter floating in the air.

2. Features: PM 10 can enter the upper respiratory tract, but some of it can be discharged through sputum, and it will also be blocked by villi inside the nasal cavity.

Extended data:

Harm of inhalable particles to human body;

1, respiratory system

The elevated concentration of PM 10 in the atmosphere is likely to cause upper respiratory tract infection and aggravate respiratory diseases such as rhinitis, chronic pharyngitis, chronic bronchitis, bronchial asthma, emphysema and pneumoconiosis.

2. Effects on cardiovascular diseases

The changes of heart rate, heart rate variability and blood viscosity caused by particulate matter can increase the risk of sudden myocardial infarction. People exposed to high concentrations of PM2.5 will increase the viscosity of blood and some albumin in blood, thus causing thrombosis.

3. Nervous system

Many inhalable particles in cities are produced by motor vehicle exhaust. Lead particles (including lead oxide and lead carbonate) produced by burning leaded gasoline diffuse into the atmosphere and enter the human body with the respiratory tract, which affects health.

4. It has carcinogenic, mutagenic and disabling effects.

Polycyclic aromatic hydrocarbons (PAHs) will be produced in the process of incomplete combustion of fossil fuels such as oil and coal and organic substances such as wood and tobacco. The discharged polycyclic aromatic hydrocarbons can directly enter the atmosphere and be adsorbed on particulate matter, especially fine particulate matter with a diameter less than 2.5 microns. ..

Polycyclic aromatic hydrocarbons (PAHs) have carcinogenic, mutagenic and disabling effects, which are extremely harmful to human health. Among them, benzo (a) pyrene (BaP) is the most carcinogenic substance, which can induce skin cancer, lung cancer and gastric cancer. In addition, polycyclic aromatic hydrocarbons in the air can also react with ozone, nitrogen oxides and nitric acid. , and transformed into compounds with stronger carcinogenic or mutagenic effects, thus posing a threat to human health.

Baidu encyclopedia-inhalable particulate matter