The air quality reflects the degree of air pollution, which is judged according to the concentration of pollutants in the air. Air pollution is a complex phenomenon. At a specific time and place, the concentration of air pollutants is affected by many factors. Man-made pollutants emitted by stationary and mobile pollution sources are one of the most important factors affecting air quality.
These include the tail gas of cars, ships and planes, industrial pollution, heating of residents' lives, garbage incineration and so on. Urban development density, topography and meteorology are also important factors affecting air quality. According to the standards of the World Health Organization, when the concentration of negative oxygen ions in the air is higher than per cubic centimeter 1000- 1500, it can be called "fresh air".
Introduction to air quality
Air pollution sources can also be divided into natural and man-made two categories. Natural pollution sources are formed due to natural causes (such as volcanic eruptions, forest fires, etc.). ), and man-made pollution sources are formed because people are engaged in production and life activities. Total suspended particulate matter refers to the general name of solid and liquid particulate matter floating in the air, and its particle size range is about 0. 1- 100 micron.
Some particles are visible to the naked eye because of their large particle size or black color, which is more than inhalable particles such as smoke and dust. Some are small enough to be observed with an electron microscope. Generally speaking, particles with a particle size below 10 micron are called inhalable particles. The concentration of inhalable particulate matter is expressed in milligrams per cubic meter of air.
Reference to the above content: Baidu Encyclopedia-Sichuan Province