(2) According to the provisions of the World Health Organization (WHO), air pollution means that if there are man-made pollutants in the outdoor atmosphere, their content, concentration and duration can cause discomfort to most residents, endanger public health in a large range and hinder the lives of humans, animals and plants.
Air pollutants can be divided into primary pollutants and secondary pollutants according to their formation process. The so-called primary pollutants refer to pollutants directly discharged by pollution sources, such as carbon monoxide and sulfur dioxide. Secondary pollutants refer to pollutants formed by chemical reaction or photochemical reaction of primary pollutants, such as ozone, sulfate, nitrate and secondary organic particles.
Common air pollutants are as follows:
(1) Sulfur compounds: sulfur dioxide (SO2), hydrogen sulfide (H2S), sulfate (SO42-), etc.
(2) Nitrogen compounds: nitrogen oxides (nitrogen oxides), ammonia (NH3), nitrate (NO3-), etc.
(3) Particulate matter: total suspended particulate matter (TSP), inhalable particulate matter (PM 10), fine particulate matter (PM2.5), etc.
(4) Volatile organic compounds (VOCs): It can be divided into alkanes, aromatic hydrocarbons, olefins, halogenated hydrocarbons, esters, aldehydes and ketones. Common VOCs are benzene, toluene, xylene, styrene, trichloroethylene, chloroform, diisocyanate and so on.
(5) Persistent organic pollutants: aldrin, dieldrin, endrin, DDT, heptachlor, chlordane, mirex, toxaphene, hexachlorobenzene, polychlorinated biphenyls, polychlorinated dibenzo-dioxins and polychlorinated dibenzofurans;
(6) Photochemical oxidants: ozone (O3), peroxyacetyl nitrate (PAN) and free radicals in the atmosphere.
(7) Carbon oxides: carbon monoxide (CO), carbon dioxide (CO2), etc.
(8) Halogen compounds: fluoride, bromine-containing compounds, etc.
Key air pollutants refer to air pollutants such as sulfur dioxide and nitrogen oxides, which are incorporated into the national economic and social development plan as binding indicators by the national and provincial people's governments according to the needs of improving the quality of the atmospheric environment, and the total emission control and reduction are determined.
Toxic and harmful air pollutants refer to air pollutants listed in the national list of toxic and harmful air pollutants, which have harm and influence on human health and ecological environment.
Atmospheric particles are solid and liquid particles suspended in the atmosphere, with particle sizes ranging from a few nanometers to 100 micron. According to the aerodynamic equivalent diameter, common atmospheric particles can be divided into total suspended particles (TSP), inhalable particles (PM 10) and fine particles (PM2.5), and their aerodynamic diameters are less than or equal to 100 micron, less than or equal to 10 micron and less than or equal to 2.5 micron respectively, among which the TSP contains PM65438.
Photochemical oxidant (Ox) is produced by photochemical reaction of nitrogen oxides and volatile organic compounds emitted from natural and man-made sources under sunlight. It mainly includes ozone (O3), peroxyacetyl nitrate (PAN), nitrogen dioxide (NO2), aldehydes (RCHO), hydrogen peroxide (H2O2) and other substances that are harmful to plants and are irritating and oxidizing. Among them, O3 is the representative, generally accounting for more than 90% of Ox, followed by PAN.
VOCs is the abbreviation of English name of volatile organic compounds. Different institutions and organizations have different definitions of volatile organic compounds to meet different management, control or research needs. American ASTM D3960-98 defines VOC as any organic compound that can participate in atmospheric photochemical reactions. The National Environmental Protection Agency (EPA) defines VOC as any carbon compound that participates in atmospheric photochemical reactions except carbon monoxide, carbon dioxide, carbonic acid, metal carbide, metal carbonate and ammonium carbonate. The World Health Organization (WHO, 1989) defines total volatile organic compounds (TVOC) as the general term for volatile organic compounds with melting point below room temperature and boiling point between 50-260℃. China's Pollutant Emission Standard for Synthetic Resin Industry (GB 3 1572-20 15), Pollutant Emission Standard for Petrochemical Industry (GB 31571-2015) and Pollutant Emission Standard for Petroleum Refining Industry.
According to the chemical structure, VOCs can be divided into alkanes (such as n-hexane, n-pentane), aromatic hydrocarbons (such as benzene, toluene, o-xylene, m-xylene, p-xylene and styrene), olefins (such as isobutylene, 1, 3- butadiene), halogenated hydrocarbons (such as chloroform, methyl bromide and trichloroethylene) and esters (such as amyl acetate).
Non-methane total hydrocarbons refer to the total number of hydrocarbons except methane (mainly C2-C8).
POPs is the abbreviation of English name "Persistent Organic Pollutants", which refers to chemical substances synthesized by human beings that can exist in the environment for a long time, accumulate through the food chain and have harmful effects on human health and the environment. These substances can cause endocrine system disorder, reproductive and immune system damage, and induce cancer and nervous system diseases. The first batch of 12 POPs listed in the Stockholm Convention on Persistent Organic Pollutants are aldrin, dieldrin, endrin, DDT, heptachlor, chlordane, mirex, toxaphene, hexachlorobenzene, polychlorinated biphenyls, polychlorinated dibenzo-p-dioxins and polychlorinated dibenzofurans.
Odor pollutants refer to all gas substances that stimulate the olfactory organs, cause unhappiness and destroy the living environment.