Radon is a radioactive gas slowly released from underground by radium that breaks down in soil, rocks, and water.
Radon continues to decay and form other radioactive particles that cling onto the lung wall.
Energy released during the decay. This energy damages to the lung cells.

The damaged cells becomes cancer cells when they improperly repaired themselves.

How does Radon gas get into your dwelling?

Simply put, air pressure difference.

 Air pressure in the soil below your basement floor is often higher
than the indoor air pressure in your basement.

The radon and soil gas are being pushed into your basement through different gaps and cracks.

The Entry Points