2020 Health Care Professionals Guide [Update] 2020 VOL 2 [Update]: September | Page 6

How Does Radon Enter the Home ?

Outdoors , where it is typically diluted to low concentrations in the air , radon poses a significantly smaller risk than it does indoors . In the indoor air environment , however , radon can accumulate to high concentrations . The magnitude of the radon concentration indoors depends primarily on the amount of radon produced in the underlying soil and bedrock , the soil permeability , and the building ’ s construction . The soil composition under and around a house affects radon levels and the ease with which radon migrates toward a house . Normal pressure differences between the house and the soil often create a slight vacuum in the home that can draw radon gas from the soil into the building . Radon gas can enter a home from the soil through cracks in concrete floors and walls , floor drains , sump pits , construction joints , around pipe penetrations , and through tiny cracks or pores in hollow-block walls . Radon may sometimes be emitted from concrete . While radon concentrations generally are highest in basements and ground floor rooms that are in contact with the soil , radon levels often are high in main floor and upper floor rooms as well . Another source of radon indoors may be radon gas released by well water during showering and other household activities . Compared to radon entering the home through soil , radon entering the home through water will be , in most cases , a small source of risk .
Radium , which naturally occurs in soils and rocks from the radioactive decay of uranium , produces radon gas that can move through the soil into a home or other building through these common entry points . Because the air pressure inside a home is often lower than the pressure in the soil around the foundation and basement floor slab , radon is easily drawn into a home due to these air pressure differences .

Radon Decay Products

Radon undergoes radioactive decay into a series of solid radioactive decay products . A large percentage of the decay products attach to ambient airborne aerosols , while some of the decay products remain unattached . The attachment rate depends on numerous factors , such as the size and concentration of ambient particles . Deposition of radon decay