Radon is a naturally occurring, tasteless, odorless, colorless radioactive gas that develops from the decay of uranium. Since uranium occurs naturally in small quantities in most rocks and soil, radon gas is continually released into soil, underground water and outdoor air. Radon gas can seep into buildings through openings such as cracks, building joints, and utility penetrations. The EPA has developed a radon zone map that indicates potential radon levels. District of Columbia is a Zone 3 which is low potential for radon exposure. However, EPA recommends that all building be tested for possible radon regardless of the geographic location or zone designation. The presence of radon gas depends on a variety of factors such as building construction and negative air pressure. The only way to find out if unhealthy levels of radon are present is to test for it.