For example, according to its chemical characteristics, air pollution can be divided into two types. What are the main pollutants of each type and what are the weather conditions?

① Reduction type (coal burning type): main pollutants: SO2, CO and particulate matter. Under the conditions of low temperature, high humidity, cloudy day, light wind and inversion temperature, pollutants are blocked above the city under the influence of local topographic conditions, which does great harm to human health and causes thousands of deaths. Events like this have happened many times, and the most typical one is the SO2 smog poisoning incident in London, England in June1952+February 65438.

② Oxidation type (automobile exhaust type): pollutants mainly come from automobile exhaust, oil-fired boilers and petrochemical production. The main pollutants are nitrogen oxides and HC, and the secondary pollutants are O3, aldehydes, ketones and peroxyacetyl nitrate. It occurs in tropical and subtropical areas with strong sunshine (subtropical high control area), at noon or afternoon with strong sunshine from August to September. The most typical is the photochemical smog in Los Angeles around 1965.