Frequently Asked Questions

Ionizing radiation is energy that travels through space as invisible rays or tiny particles coming from natural and man-made sources (for example, soil and rock, building materials, medical and industrial equipment). It has enough energy to remove electrons from atoms and molecules, which can damage cells and DNA; at high doses or over long periods this can increase the risk of cancer and other health effects.

In and around homes and other buildings, most everyday ionizing radiation comes from natural background sources. Because almost all rocks, minerals and soil contain small amounts of naturally occurring radioactive elements, many common construction materials – such as concrete, brick, natural stone and some decorative tiles or countertops – also contain very small amounts of radioactivity.

Low levels of additional radioactivity can also be found in some older or antique items, such as uranium-glazed ceramics or uranium glassware, where uranium or, historically, radium was used in glazes or paints.

Radon is a colorless, odorless radioactive gas that forms naturally in soil and rock. It can enter homes and other buildings from the ground through cracks in foundations, gaps around pipes and cables, crawlspaces, sumps and other openings. Once indoors, radon can build up, especially in lower levels and in areas with limited ventilation.

Long-term exposure to elevated radon levels is a well-established risk factor for lung cancer. In the United States, radon exposure is associated with thousands of lung cancer cases each year, and the risk increases as indoor radon levels and the duration of exposure rises.