Tell the reasons for the formation of smog and what measures to take.

As a natural phenomenon, smog has three factors. First, the phenomenon of static wind in the horizontal direction has increased. In recent years, with the rapid development of urban construction, buildings are built higher and higher, which increases the friction coefficient of the ground and weakens the airflow when passing through the urban area. The increase of static wind phenomenon is not conducive to the diffusion and dilution of atmospheric pollutants to the periphery of urban areas, and it is easy to accumulate high-concentration pollution in urban areas. The second is the phenomenon of vertical inversion. The inversion layer is like a pot cover over a city, which causes the inversion phenomenon that the temperature at high altitude is higher than that at low altitude. Under normal climatic conditions, pollutants diffuse from low altitude with high temperature to high altitude with low temperature and are gradually discharged into the atmosphere. Under the inversion phenomenon, the low-altitude temperature is lower, which leads to the retention of pollutants and cannot be discharged in time. The third is the increase of suspended particulate matter. In recent years, with the development of industry, the increase of motor vehicles, the discharge of pollutants and the increase of suspended solids in the city have directly led to the decrease of visibility and made the whole city look gray.

First of all, a smog index forecast and a smog weather early warning mechanism should be established. Set up ground-based optical observation points in cities to monitor aerosol optical thickness with satellite remote sensing data; At the same time, set up horizontal visibility observation stations and vertical visibility observation stations in the surrounding areas of the city to carry out horizontal visibility and vertical visibility observation and directly provide public services for smog weather; Carry out atmospheric boundary layer detection, regularly grasp the relationship between boundary layer characteristics such as inversion and haze weather, understand the influence of industrialization and urbanization on atmospheric boundary layer structure, improve the accuracy of haze weather forecast, and improve the ability of haze weather monitoring and prevention; Strengthen solar radiation monitoring and assess the impact of atmospheric smog on agricultural production and climate change.

Only by combining the establishment of a smog weather forecast system with the establishment of a dynamic pollution control system and a decision-making system to control the emission of pollution sources can we effectively deal with smog. Judging from the current situation, urbanization and industrialization are the main factors causing smog, and a meteorological feature of smog weather is that there is an air stagnation area in its area. Some developed countries abroad try to solve the harm of smog by dynamically adjusting social production under different meteorological conditions, the essence of which is to adjust the total amount of pollution sources. For example, in the United States, once the air stagnation zone is detected in a certain area, the industrial gas emission in that area will be controlled, and it can be fully discharged under the condition of good atmospheric conditions and strong air diffusion ability.

Secondly, strict measures should be taken to limit automobile exhaust emissions and industrial gas emissions in order to eliminate or reduce the harm of smog to cities. At the same time, smog prevention should be considered as a whole among urban agglomerations. As a regional climate disaster phenomenon, only through regional cooperation can we achieve the best governance effect.

Finally, in urban planning, we should pay attention to the study of the sinking distance between the urban updraft and the suburbs, and arrange the heavily polluted industrial enterprises outside the sinking distance to prevent the pollutants discharged by these factories from flowing from the near ground to the urban area; Satellites should also be built outside the circulation of urban heat islands to avoid mutual pollution. It is necessary to fully consider the diffusion conditions of the atmosphere and reserve air passages. Increase urban green space, so that urban green space can exert environmental benefits such as smoking, dust removal, air filtration and beautifying the environment, thus purifying urban atmosphere and improving urban air quality.

Attention should be paid to exercise in this kind of haze weather: haze weather is easy to stimulate the human respiratory and circulatory system, especially in the morning when the human blood concentration is high and the body stretching function is poor. At this time, exercise is easy to sprain the body and induce myocardial infarction and pulmonary heart disease. Generally speaking, regardless of special weather systems such as cold air, typhoon, front and shear line, the air quality is the best and the visibility is the highest in the evening 17 ~ 19. Therefore, the daily exercise time should be set at night 17 to 19. In addition, the amount of exercise and intensity should be moderately reduced in foggy weather, and places with more trees and grass are better choices.

Generally speaking, visibility less than 10 km is a haze phenomenon, 5 to 8 km is a moderate haze phenomenon, 3 to 5 km is a severe haze phenomenon, and less than 3 km is a serious haze phenomenon.