Factors affecting indoor air pollution with radon.

Radon is a radioactive gas. It is a decay product of natural radium-226 and is found everywhere outdoors and indoors. It is released from the ground and building materials into the air. It is trapped in the lung, decays, and deposits its alpha particles energy in the lung tissue. It has different hazardous ending by lung cancer. Radon enters houses primarily from the ground through gaps in the building structure. It also enters from the building materials of the house and the supply water system. The present study aimed to explore the factors affecting the indoor air radon concentration in different regions of Cairo, Egypt. It also aimed to define methods of mitigation. MATERIAL AND METHOD The concentration of indoor air radon of 190 buildings (homes and work places) in different regions of Cairo was measured by passive technique of Solid State Nuclear Track Detectors with Allyldiglycol Carbonate. Data about the buildings characteristics were achieved by using a questionnaire. These characteristics included; percent of ceramic surface area in the building, type and duration of ventilation, years of construction of the building, type of wall cover used, and floor level. The relation between the building characteristics and concentration of indoor air radon was studied. RESULTS The results of the study showed that; buildings with ceramic have more indoor radon concentration than building without ceramic and increase the surface area of ceramic increases the radon concentration. Lower hours of ventilation result in higher levels of radon concentration. Mechanical ventilation result in higher level of indoor air radon concentration than natural ventilation. The more recent the building, the more radon concentration. Covering the wall with ceramic and plastic result in higher level of radon while covering it with masys and paper result in lower level. The lower the floor, the higher the indoor air radon concentration. CONCLUSION To decrease the level of indoor air radon concentration and reduce its harmful effects it was recommended to limit the use of ceramic in the building construction, increase the hours of ventilation specially the natural one in which new aeration works to wash the accumulated amounts of radon, use masys as wall cover. Restrict the use of underground floors in the building especially in areas where more activity is predicted as malls and underground Metro