Air Quality and Population Exposure in Urban Areas: Potential Co-Benefits of Alternative Strategies

Even though much progress has been achieved through dedicated approaches to improving air quality in many European cities, there are various threats which still remain unchanged. According to the World Health Organization, outdoor air pollution was linked to 3.7 million deaths in year 2012. As climate changes, the frequency of days with harmful levels of air pollutants may significantly increase causing exacerbation of cardiovascular and respiratory diseases. The aim of this study is to conduct health impact assessment by utilizing regionally and spatially specific data in order to assess the influence of alternative emission strategies on human health. In the first stage of this investigation, a modeling study was carried out using the Weather Research and Forecasting (WRF) model coupled with Chemistry (WRF/Chem; Grell et al., 2005) to estimate ambient concentrations of air pollutants. The model set-up included a nesting approach, where three domains with horizontal resolution of 18 km, 6 km and 2 km were defined. The investigation area included the city of Munich (1.5 million inhabitants). The model performance has been evaluated against available air quality observations from the monitoring database "AirBase". The chemical species including O3, NO, NO2 and PM10 simulated by WRF/Chem compare favorably with the observations. The model performs especially well in resolving the observed O3 concentrations. In the ongoing study, different emission reduction scenarios are compared to a baseline 2009 scenario based on Germany's National Emissions Inventory. To investigate health effects associated with air pollution concentrations a local-scale health impact assessment (HIA) will be conducted. Concentration-response functions (CRFs) link the change in mortality rates to the change in concentrations of air pollutants. CRFs are applied to population-weighted mean concentrations to estimate relative risks and hence estimate numbers of attributable deaths and associated life-years lost. The health benefits that we assume with introducing alternative air quality strategies can be used to provide options for future policy decisions to achieve the reduction of emissions and thereby premature deaths.