PARTICLES OF DIFFERENCE

摘要

Tropospheric aerosols are of current regulatory and scientific concern principally because of their association with impairment of human health and possible influences on climate change. Atmospheric aerosols are also directly associated with visibility reduction, with long-range transport and deposition of air pollutants, and with influences on atmospheric chemical processes. The prospect of new regulations on particulate matter of aerodynamic diameter less than 2.5μm, makes it mandatory that the processes governing the loading and distribution of these aerosols be sufficiently well understood to permit development of effective and efficient strategies to achieve prospective standards. Aerosol particles are highly heterogeneous, from location to location, from time to time at a given location, as a function of size at a given time and location, and from particle to particle within a given size fraction. Thus aerosols must be considered a complex of substances not a single substance. This situation makes it clear that no single control strategy will be effective in reducing aerosol loading and that effective control strategies must be tailored to specific locations. Development of such tailored control strategies must rely on understanding of the processes governing the loading of aerosols as represented in models and as demonstrated by comparison with observations. Many new techniques are available to provide the needed understanding of aerosol properties and processes, but acquiring this understanding will require a substantial commitment of effort and resources.