Final answer:
The U.S. EPA recommends radon mitigation methods that lower radon levels in buildings, notably active soil depressurization (ASD), where a system vents radon from beneath a building to the outside.
Step-by-step explanation:
The Radon mitigation method generally recommended by the U.S. Environmental Protection Agency (EPA) involves reducing radon levels in homes and buildings. This process typically includes sealing cracks and openings where radon can enter and implementing ventilation improvements to lower radon concentrations. The EPA has set an action level of 4 pCi/L, and if testing reveals radon levels at or above this threshold, mitigation measures are advised to protect the health of occupants.
Mitigation of radon gas buildup in residential and commercial structures can include active soil depressurization (ASD), which is the most common and often considered the most reliable technique. ASD involves installing a pipe system and fan to pull radon from beneath the building and vent it to the outside, preventing it from entering the indoor environment.