With the development of civilization,visibility in most of the urban areas comes to be a big problem.The reason and mechanism that attribute to haze are discussed in this paper.The latest policy in the US is introduced as well.The main factors which cause haze can be divided into two aspects: environmental pollution factor and meteorological factor.Visibility can be calculated from measurements of atmospheric chemical components.The visibility of Beijing in 2001 is calculated as an example.Judging from the calculation,spring is the clearest season of the whole year (above 11 km according to the calculated results),while summer is the poorest (no more than 9 km),which agrees with the real monitoring record.
dust hazevisibility, particulate mattervisual air quality, atmospheric chemistry
NETL
NSTL
万方数据
维普
