Which one should I trust in the US standard or the national standard for PM2 5?

PM, the full name of particulate matter in English. Scientists use this to indicate the amount of such particles per cubic meter of air, and the higher this value, the more severe the air pollution. Respirable particulate matter and total suspended particulate matter in urban air quality** or weekly reports are two of the most familiar air pollutants.

Inhalable particulate matter, also known as PM10, refers to particulate matter with a diameter greater than microns, equal to or less than 10 microns, which can enter the human respiratory system; Total suspended particulate matter is also known as PM100, i.e. particulate matter with a diameter of 100 microns or less. The main products produced are the residues emitted through combustion in the process of daily power generation, industrial production, automobile exhaust emissions, etc., most of which contain toxic substances such as heavy metals. Generally speaking, coarse particulate matter with a particle size of microns to 10 microns mainly comes from road dust. Fine particulate matter below microns (mainly from the combustion of fossil fuels (e.g., motor vehicle exhaust, coal burning), volatile organic compounds, etc.

Experts and medical experts believe that haze caused by fine particulate matter is even more harmful to human health than sandstorms. Particulate matter with a particle size of more than 10 microns will be blocked out of the human nose; Particulate matter with a particle size between microns and 10 microns can enter the upper respiratory tract, but some of them can be excreted through sputum, etc., and will also be blocked by the villi inside the nasal cavity, which is relatively less harmful to human health; Fine particles with a particle size of less than microns, the diameter of which is equivalent to 1 10 of the size of a human hair, are not easy to block. When inhaled, it can directly enter the bronchial tubes, interfering with the gas exchange in the lungs, causing diseases such as asthma, bronchitis and cardiovascular disease.

Each person inhales an average of about 10,000 liters of air per day, and the fine dust that enters the alveoli can be quickly absorbed and directly enter the blood circulation and distribute to the whole body without liver detoxification. Second, it impairs the ability of hemoglobin to deliver oxygen, resulting in loss of blood. For patients with anemia and circulatory disorders, there can be serious consequences. For example, it can aggravate respiratory diseases and even cause heart diseases such as congestive heart failure and coronary arteries.

In short, these particles can also enter the blood through the bronchi and alveoli, and the harmful gases and heavy metals in them are dissolved in the blood, which is more harmful to human health. The physiological structure of the human body determines that there is no ability to filter or block, but the harm to human health has gradually exposed its terrifying side with the progress of medical technology. In the European Union, it leads to a decrease in the average life expectancy of people.

It can also be a vector for viruses and bacteria, contributing to the spread of respiratory infections. At present, major developed countries in the world, as well as Japan, Thailand, and India in Asia, will be included in the air quality standards. The saddest thing is that it has not yet been included in China's ambient air quality indicators, so this has become the root cause of the direct conflict between the data of the US embassy and the official data.

The standard is that the 24-hour average concentration is less than 75 micrograms of cubic meters.

Refers to atmospheric particles with a diameter of less than or equal to microns, also known as particles that can enter the lungs.

The particle size is small, contains a large number of toxic and harmful substances, has a long residence time in the atmosphere, and the transportation distance is long. In short, it will affect air quality, which will have a greater impact on human health and the quality of the atmospheric environment. Although it is only a small part of the composition of the Earth's atmosphere, it has a significant impact on things like air quality and visibility.

Its filtration methods include air conditioners, humidifiers, air purifiers, etc., and you can also raise some green plants, plant leaves have a large surface area, which can absorb harmful gases and adsorb, in addition, outdoor sports should be avoided when the level is high.

Main hazards: 1. Although fine particulate matter is only a small component of the earth's atmospheric composition, it has an important impact on air quality and visibility. Compared with coarser atmospheric particulate matter, fine particulate matter has a small particle size, is rich in a large number of toxic and harmful substances, and has a long residence time in the atmosphere and a long transportation distance.

2. Therefore, it has a greater impact on human health and atmospheric environmental quality. Studies have shown that the smaller the particles, the greater the harm to human health. Fine particulate matter can drift to a greater distance, so it has a large area of influence.

3. Fine particulate matter is more harmful to human health, because the smaller the diameter, the deeper the part that enters the respiratory tract. Particulate matter with a diameter of 10 m is usually deposited in the upper respiratory tract, and particles below 2 m can penetrate deep into the bronchioles and alveoli. After fine particulate matter enters the alveoli of the human body, it directly affects the ventilation function of the lungs, making the body easy to be in a state of hypoxia.

The standard value is a 24-hour average concentration of less than 75 micrograms cubic meters.

China's 24-hour standard value is excellent: 0-50; Good: 50-100; Light pollution: 100-150; Moderate pollution: 150-200; Heavy pollution: 200-300; Severe pollution: greater than 300 and above.

The standard was proposed by the United States in 1997, mainly to more effectively monitor the small particulate matter that appeared with the increasing development of industrialization and was ignored in the old standard. The index has become an important indicator for measuring and controlling the level of air pollution.

of the protection method

1. You can use an air purifier

Although the purifier has an exaggerated role in publicity, its role in purifying the air is still undoubted, and when the air is bad, you can use the purifier at home to help purify the toxic substances in the air, clean the air and improve the breathing environment.

2. Properly open windows for ventilation

Dry weather makes germs easy to gather, whether it is a large stall in the air or some indoor toxic air, such as formaldehyde, polyethylene, second-hand smoke, etc. on the pure wall, etc., all of which are very harmful to the body. It is necessary to choose a good weather when the pants are erected and properly open the window for ventilation to make the indoor air circulation and avoid a large number of bacteria from accumulating.

3. You can raise green plants at home

The choice of green plants in the living room is also very crucial, some green can effectively adsorb indoor toxic gases, and play a certain role in the treatment of indoor polluted air. Spider plant, aloe vera, agave, yueji, tiger tail orchid and other plants can not only beautify the environment, but also play a role in purifying the air and increasing the amount of oxygen.

The national air quality standard (GB3095-2012) stipulates the limits of air pollutants, mainly the daily average concentration limit for one day, the twelve-hour sliding daily average concentration limit, and the monthly average concentration limit for fifteen days

Daily average concentration limit: 75 g m;

12-hour sliding daily average concentration limit: 50 g m;

Fifteen-day moon level amusement average concentrated lead cherry degree limit: 35 g m.

In addition, the Standard for Average Daily Concentrations of Air Pollutants (GB T16157-1995) stipulates a maximum one-hour concentration limit of 150 g m.

In addition, in order to better protect the environment, the World Health Organization (WHO) also recommends lowering the daily average concentration limit to 25 g m, the 12-hour sliding daily average concentration limit to 20 g m, and the 15-day monthly average concentration limit to 15 g m.

Fine particulate matter is also known as fine particles, fine particles, . Fine particulate matter refers to particulate matter in ambient air with an aerodynamic equivalent diameter of less than or equal to microns. It can be suspended in the air for a long time, and the higher its concentration in the air, the more serious the air pollution.

Although it is only a small component of the Earth's atmosphere, it has important implications for air quality and visibility.

Atmospheric particulate matter is a general term for a variety of solid and liquid particulate matter present in the atmosphere. Various particulate matter is evenly dispersed in the air to form a relatively stable and large suspension system, that is, an aerosol system, so atmospheric particulate matter is also called atmospheric aerosols.

China's standard is an annual average concentration limit of 35 micrograms, and a 24-hour average concentration limit of 75 microgram cubic meters. It refers to particulate matter in the atmosphere with an aerodynamic equivalent diameter of less than or equal to microns, also known as particulate matter that can enter the lungs (there is no standard Chinese name).

Air quality grade 24-hour average standard value:

Excellent: 0 35 g m3

Good: 35-75 g m3

Light contamination: 75 115 g m3

Moderate pollution: 115 150 g m3

Heavy pollution: 150 250 g m3

Severe pollution greater than: 250 g m3 and above.