Particulate Matter in the Urban Atmosphere: Concentration, Distribution, Reduction – Results of Studies in the Berlin Metropolitan Area

Urban agglomerations are places of increased emissions of anthropogenic pollutants into the atmosphere. Since most of these pollutants are harmful to humans, reduction of their ambient concentrations is a major issue of environmental policy on international, national, and local levels. According to Wiederkehr and Yoon (1998), air pollutants can be grouped into major and trace or hazardous air pollutants. Major air pollutants comprise six classical pollutants: sulphur dioxide (SO2), airborne particles, nitrogen dioxide (NO2), carbon monoxide (CO), lead (Pb), and ozone (O3). Hazardous air pollutants can be found in much smaller concentrations than major air pollutants and include different chemical, physical, and biological agents, like volatile organic compounds (VOCs), radio-nuclides, and micro-organisms. Concentrations of air pollutants are not only governed by various physical, chemical, or biological processes within the atmosphere, but also by anthropogenic actions. Levels of most air pollutants in the urban atmosphere are linked to economic activity. They are typically increasing with income per capita until a turning point is reached. Beyond this point, concentration levels decrease with increasing income (Fenger 1999). Therefore, if urban ecology is defined as a multidisciplinary approach, including natural and social sciences, to improve conditions of life for humans in cities (Endlicher et al. 2007), air quality and related pollution problems are a major issue of urban ecology where natural and anthropogenic aspects are intimately interwoven.