Identification of natural radon gas emission zones in Mashhad and implementing its pollution reduction system at the site-scale

The natural emission of radon gas is an emerging phenomenon that modern lifestyles have turned into a potential danger to humans. It is a gas that has no physical properties that can be seen or understood by humans. Therefore, it is much more dangerous than other gaseous pollutants. This natural gas inside a building is determined by both the terrain on which it is built and the composition of its constructed materials. Today, the world's developed countries have prepared Radon atlases in their critical locations and big cities. As the second most important city in the country, the Mashhad, which is also considered one of the most touristic cities in Iran, is doubly important. In this study, first, the structural geology condition of the Mashhad in terms of Radon emission has been investigated, and then Radon has been measured. Using Arc GIS software, natural Radon emission zoning maps at urban and geological scales have been prepared. Also, a residential unit in one of the critical areas of natural Radon emission has been selected. A corrective method has been adopted to reduce Radon. The methods applied to the structure were able to significantly reduce radon gas by 27 to 50 percent. Given that natural radon emissions from subsurface rocks and fractures are present in all parts of the world. So identifying critical areas (with high radon emissions) can provide special control measures at the local and site scale buildings that reduce the risks of this natural gas.