Are smog and PM2.5 the same thing?

　　When it comes to PM2.5, many people have conceptual errors, thinking that PM2.5 is smog and that the two are the same thing. But in fact, the two are not equal to each other, but should be included in the relationship. So why is there such a misunderstanding? To clarify the relationship between the two, we must first clarify two concepts:

　　What is PM2.5

　　PM is the abbreviation of Particulatematter in English, and 2.5 represents the diameter of this particle. Particulate matter is generally divided into two categories: PM2.5 and PM10. PM2.5 refers to particulate matter with a diameter less than or equal to 2.5 microns, which is equivalent to 1/20 of the diameter of a human hair and has reached the critical value of the alveoli. Fine particulate matter below PM2.5 can no longer be blocked by the human body's nasal cavity and throat. They can go all the way down, enter the bronchioles and alveoli, and then enter the capillaries through the alveolar walls, and then enter the entire blood circulation system. Causes damage to the human respiratory and cardiovascular systems.

　　PM10 is particulate matter with a diameter less than or equal to 10 microns, and its volume is 64 times that of PM2.5. The throat is the terminal station of PM10. The mucus secreted on the surface of the throat will stick to them and can be discharged through spitting, so it is not harmful to the human body.

　　What is smog

　　Smog weather is a state of air pollution. Smog is a general expression that the content of various suspended particulate matter in the atmosphere exceeds the standard. The haze we often talk about is actually a combination of fog and haze, but fog is fog and haze is haze. There is a big difference between fog and haze. Simply put, the tiny water droplets in the air are fog, which is a liquid, while haze is a solid, which is composed of tiny dust particles, , , inhalable particles and other particles in the air. It can make the air turbid and reduce visibility, the combination of which is smog. The combination of the two can be vividly compared to a child playing in mud, mixing sand, mud and water together, making it mixed and dirty.

　　The relationship between the two

　　Many people confuse the two with one concept, thinking that smog is PM2.5. In fact, PM2.5 is just one component of smog. The two are inclusive, not reciprocal. The reason for this conceptual error is that PM2.5 particles are the main component of haze, are the most harmful to the human body, and are the "culprit" of haze weather. Therefore, the key to controlling haze is to solve the PM2.5 problem. Therefore, many news or articles will use PM2.5 as the "synonym" for haze, causing a misconception among the public.

　　PM2.5 contributes to the formation of haze weather, and haze weather can further aggravate the accumulation of PM2.5. On hazy days, the humidity in the air is high, and fog droplets provide a place for adsorption and reaction. Pollutant gases such as sulfur dioxide and nitrogen oxides in the air will generate PM2.5 particles through atmospheric chemical reactions. The accumulation of PM2.5 also accelerates the generation of haze, and the two interact with each other.

　　Compared with coarser atmospheric particles, PM2.5 has a small particle size, a large area, and strong activity. It is easy to carry toxic and harmful substances (such as heavy metals, bacteria, etc.), which will contribute to the spread of diseases. It also stays in the atmosphere for a long time and is transported over a long distance, so it has a greater impact on human health and the quality of the atmospheric environment.