Talking about the burning wasteland

Perceived air pollution: factory emissions, automobile exhaust, land reclamation, forest fires, kitchen smoke (including roadside barbecues), dust (including construction sites) and so on.

Opinion: 1. Overview of air pollution

Even if the sky is clear, the atmosphere around us is not as clear as it looks. The air is full of invisible solids, liquids and gases, such as pollen, bacteria, smoke and dust, moisture and so on. The so-called air pollution means that the air contains one or more pollutants, whose quantity, nature and time will do harm to the life of human beings, plants and animals, damage property, or interfere with the comfortable living environment, such as the existence of odor. In other words, as long as a substance exists in sufficient quantity, nature and time and has an impact on human beings or other creatures and property, we can call it an air pollutant; And the phenomenon caused by its existence is air pollution. We need to know the composition of clean air before we know what will cause pollution when it enters the air. The composition of clean air is shown in table 1: what we usually call "air pollutants", such as nitrogen dioxide and ozone. The content of sulfur dioxide, carbon monoxide and other substances in clean air is very small; But in the case of pollution, some kinds of these specific substances will increase greatly. In other words, the abnormal increase of some substances in the air will produce air pollution.

Second, the types of air pollutants

There are many kinds of air pollutants, and their types may be solid particles, drops or gases, or a mixture of these types. What are the definitions of air pollutants in Chinese laws and regulations at present? According to the definition and relevant regulations of the Air Pollution Prevention Law, air pollutants can be divided into four categories, namely gaseous pollutants (including sulfur oxides, carbon monoxide, nitrogen oxides, hydrocarbons, chlorine, gasified hydrogen, fluoride, chlorinated hydrocarbons, etc. ), particulate pollutants (including suspended particulate matter, gold bureau smoke, black smoke, acid fog, dust, etc. ), as well as secondary pollutants (pollution caused by photochemical reactions of pollutants in the air). Common air pollutants include suspended particles, carbon monoxide, sulfur oxides, nitrogen oxides, hydrocarbons, etc., which are mostly caused by human factors. In China's laws and regulations, most air pollutants (such as chimney emissions, automobile emissions, etc.) are produced by human factors. ) have "emission standards" to regulate their own emissions.

Three. Air pollution index

The pollutant standard index (PSI) refers to the index determined by the US Environmental Protection Agency and other institutions, and the value from 0 to 500 represents the degree of air pollution. The relationship between the index value and health impact is divided into the following five levels:

Index value 0 ~ 50

5 1~ 100

10 1~ 199

200~299

300~350

Good health effect

(good)

medium

(moderate)

serious

(unhealthy)

Extremely bad

(Very unhealthy)

harmful

(danger)

Air pollutants include smoke, steam, carbonized paper, dust, soot, coal dust, carbon dust, gas, mist, dust, particulate matter and radioactive substances.

Air pollution prevention and control

The prevention and control of air pollution is a huge systematic project, which requires the joint efforts of individuals, collectives, countries and even countries all over the world. The following measures can be considered:

1, reducing pollutant emissions. Reforming the energy structure, using pollution-free energy (such as solar energy, wind energy and hydropower) and low-pollution energy (such as natural gas), pretreating fuel (such as desulfurization before burning coal) and improving combustion technology can reduce pollution emissions. In addition, before pollutants enter the atmosphere, some pollutants in waste gas can be eliminated by dust removal and smoke elimination technology, condensation technology, liquid absorption technology and recycling technology, so as to reduce the amount of pollutants entering the atmosphere.

2, control emissions, make full use of the self-purification ability of the atmosphere. Different meteorological conditions have different atmospheric capacity of pollutants, and the same pollutant discharge will cause different pollutant concentrations. For areas and time periods with strong wind, good ventilation, strong turbulence and strong convection, the atmosphere has strong diffusion and dilution ability and can accept more activities of factories and mines. In the area and time period of inversion, the diffusion and dilution ability of the atmosphere is weak, and it cannot accept more pollutants, otherwise it will cause serious air pollution. Therefore, effective emission control should be carried out in different regions and different time periods.