About radon

Radon gas - an inert heavy gas (7.5 times heavier than air), has no odor, no color, and detected only by special devices - radiometers radon. Sources of radon in indoor air are primarily geological space under the building, construction materials, of which constructed the building (eg, granite, pumice, expanded clay, brick red clay), used water and cooking gas. Open space radon is not dangerous. In confined spaces, mostly on the lower floors, if they are not ventilated, the gas accumulates and with inhaled into the lungs of man. Radon and its decay products emit alpha-particles are dangerous, which destroy living cells. Adhering to the microscopic dust particles, alpha-particles produce radioactive aerosol. By inhalation of air containing this aerosol is irradiated cells of the respiratory organs. 

Significant exposure to radon in indoor air (200 Bq/m3) can trigger growth of cancer cells and leukemia. On the degree of danger attributed to radon main source of human exposure is from natural causes