The results of numeric simulation indicate that global climate change will lead to an average rise of about 2 degrees in ambient temperature in the Ruhr area by the end of the century. This increase will have many consequences, including an intensification of the urban heat island effect as a result of an increase in the prevalence of clear, low-wind weather conditions. This will lead not only to greater thermal stress for the population but also to a change in air pollutant concentrations. Among these pollutants, ozone is of special interest, as the ozone concentration will increase with rising temperatures. Preventative urban planning measures should be taken to counteract increased thermal stress and ozone concentrations. These measures include various possibilities, such as the creation of green areas on buildings and parks in cities, reducing energy consumption by more economical use and more efficient thermal insulation and, as a general principle, the provision of reversible shading which would provide the required protection against solar radiation in the summer but would not present an obstacle to solar radiation in the winter.