Evolution of the air pollution in SW Germany evaluated by the long-term air quality index LAQx

The air quality index LAQx (Long-term Air Quality Index), which has been recently developed to evaluate the long-term integral air quality related to well-being and health of people, was applied to analyse the evolution of air pollution from 1985 to 2005 at different urban and rural sites in SW Germany. The LAQx method including the air pollutants taken into account is briefly discussed. LAQx is grouped into six classes according to the German school grade system, i.e. LAQx class 1 indicates a very good air quality, while very poor air quality is described by LAQx class 6. For an additional differentiation, the six LAQx classes are subdivided into LAQx values based on the decimal system. In accordance with the trends of the air pollutants taken into account in LAQx, the results show decreasing LAQx values at urban sites, which reflect an improvement of the integral air quality. In 1985 it was very poor and poor, respectively, whereas it reached the sufficient and satisfying level in 2005. For the rural sites, where LAQx could be determined only from 1995 to 2005, it fluctuated around a mean level indicating good to satisfying air quality but without any decreasing tendency. Differences of LAQx between the investigated sites were primarily caused by different local emission conditions. The trend of decreasing LAQx values, i.e. improvement of the integral air quality, was modified by distinctly higher LAQx values in years characterised by a relatively high portion of consecutive extremely hot summer days like during the heat waves in 2003 in Central Europe, which particularly increased the ozone concentration.