Abstract: With the development of industry and the increase of motor vehicles, the increases of pollutant emissions and atmospheric particulates have been reducing the atmospheric visibility. Research achievements indicate that PM2.5 is the main cause of reduced visibility. This article introduces different aspects of PM2.5, such as its definition, component and origin, harm, relationship with visibility, monitoring technologies, standards and preventing methods.

Key words: PM2.5, dust haze weather, atmospheric particulates, visibility