In the past, meteorological departments often used PM11 as an indicator to monitor air pollution, but PM2.5 can be directly inhaled into the lungs, which is more harmful than PM11 because of its strong penetration. PM2.5 "ultrafine dust" mainly comes from motor vehicle exhaust dust, fuel dust, sulfate, catering oil dust, building cement dust, coal dust and nitrate, and is an important part of harmful fine particles in smog.

Meteorologists and medical experts believe that haze weather caused by fine particles is even more harmful to human health than sandstorms. Particles with a particle size of more than 11 microns will be blocked out of people's noses; Particles with a particle size of 2.5 microns to 11 microns can enter the upper respiratory tract, but some of them can be excreted through sputum, and they will also be blocked by villi inside the nasal cavity, which is relatively harmless to human health; However, fine particles with a particle size of less than 2.5 microns are not easily blocked. After being inhaled into the human body, they will directly enter the bronchi, interfere with the gas exchange in the lungs, and cause diseases including asthma, bronchitis and cardiovascular diseases.

The dust entering the alveoli can be quickly absorbed, directly enter the blood circulation without liver detoxification, and distribute all over the body, which impairs the ability of hemoglobin to transport oxygen. It may have serious consequences for patients with anemia and blood circulation disorders. For example, it can aggravate respiratory diseases and even cause heart diseases such as congestive heart failure. These particles can also enter the blood through bronchi and alveoli, and harmful gases and heavy metals are dissolved in the blood, which is more harmful to human health. The physiological structure of the human body determines that it has no ability to filter and block PM2.5, but the harm of PM2.5 to human health has gradually exposed its horrible side with the progress of medical technology.

In EU countries, PM2.5 has reduced people's average life expectancy by 8.6 months. PM2.5 can also be a carrier of viruses and bacteria, which contributes to the spread of respiratory infectious diseases. At present, major developed countries in the world and Japan, Thailand and India in Asia have listed PM2.5 in air quality standards.

Fog has always been known as the "killer", and pollutants such as industrial waste gas, automobile exhaust, dust in the air, bacteria and viruses in the air are attached to these water droplets. In daily life and travel, these substances will have an impact on the human respiratory tract, and it is easy to cause acute upper respiratory tract infection (cold), acute tracheobronchitis and pneumonia, asthma attacks, and induce or aggravate chronic bronchitis. According to experts' analysis, toxic substances in the atmosphere adsorbed by PM2.5 are absorbed by the body after entering the respiratory tract, and the impact on the body is all-round. Fog is made up of invisible water droplets, but haze is made up of invisible particles and flying dust, which is very harmful to health.

In recent 31 years, the public smoking rate in China has been declining, but the prevalence of lung cancer has increased by more than four times. At present, it is generally believed that this may have a certain relationship with the increase of haze days. Many people have compared haze weather to nature's "smoking room". Not only the foggy weather with very low visibility will have an impact on human health, but also the foggy and cloudy weather will have the same problem. Hazy days also have a serious impact on cardiovascular and cerebrovascular diseases, which will hinder normal blood circulation, lead to cardiovascular diseases, hypertension, coronary heart disease, cerebral hemorrhage, and may induce angina pectoris, myocardial infarction, heart failure, etc., and cause pulmonary heart disease in chronic bronchitis. The wind can blow away the smog, and it is still necessary to solve the industrial pollution. The whole people in Qi Xin fight against smog and protect the environment. They still have to wear masks when they go out in foggy days. Pu Weixin has Tmall imported from the United States, which can effectively filter pm2.5