Study on the visibility reduction caused by atmospheric haze in Guangzhou area

In recent years the pollution of aerosol is getting worse and worse in Guangzhou area. The haze weather mainly occurs from October to April of the following year, resulting in visibility deterioration. From the beginning of the 1980's the visibility dramatically deteriorated, obviously increasing haze weather, in which there are three big fluctuations, respectively showing the periods of pollution of dust, sulphate and dust, fine particle from photochemical process and sulphate and dust accompanying the development of economy. The long-term tendency of visibility caused by fog and light fog does not have the tendency due to human activity or economical development and the variation mainly show the inner interannual and interdecadal variation of climate. The deterioration of visibility has close relation to the fine particles in Guangzhou area, with half of PM sub(10) surpassing the limits set by national second graded standard, meanwhile, all values of PM sub(2.5) rise above the day-mean limits of American national standard, indicating very high fine particle concentration. The ratio of PM sub(2.5) to PM sub(10) is also very high, reaching 62% - 69%, especially higher in dry seasons than in rainy seasons.