Air pollution amongst other forms of pollution is a greater global threat than Ebola and HIV, according to warnings by the World Health Organisation.
About 28,000 people in the UK die every year from air pollution.
External air pollution is critical for public health not only in larger cities, such as London and Glasgow, but also in smaller cities and towns, when dwellings are adjacent to major roads or rail lines (unless electrified). In such situation natural ventilation can drastically increase indoor levels of NOx and other toxins. Careful thought needs to go into designing an appropriate ventilation strategy, which could e.g. involve active carbon filters or demand controlled ventilation, in order to minimise ventilation rates whilst maintaining a good indoor environment.