Radon is a colorless, odorless, and tasteless gas that is present in varying amounts in the ground and in water. Radon is produced by the natural radioactive decay of uranium deposits in the earth. Prolonged exposure to radon in high concentrations can cause cancer. The EPA has set guidelines for radon levels in residential buildings.
The EPA recommends that mitigation measures be undertaken in residential buildings when radon concentrations are 4 picocuries per liter (4 pCi/L) of air and above. The radon concentration in a house varies with time and is affected by the uranium-radium content in the soil, the geological formation beneath the house, the construction of the house, rain, snow, barometric pressure, wind, and pressure variations caused by the periodic operation of exhaust fans, heating systems, fireplaces, attic fans, and range fans. Radon concentrations are variable and may be high in one house and low in an adjacent house. To determine if a house has a radon problem, it must be tested.
The EPA has mapped out Radon and divided the country into Zones. The map for California can be found by clicking HERE. San Diego is in a Zone with low amounts of Radon Gas. San Diego is in Zone 3 with predicted indoor Radon levels of less than 2 pCi/L which is less than the level at which the EPA considers it a hazard.
Therefore most home inspectors do not offer Radon gas testing in San Diego. According to the EPA, the test results would almost certainly come back negative. Inspectors would have to carry additional E&O insurance, which simply would not make financial sense. There are some home inspectors who will test for Radon.
Test: A long-term test is the most accurate method of determining the average annual radon concentration. However, because time is usually limited, there is a three- to seven-day test that uses a charcoal canister. It is available from most home do-it-yourself stores or through radon testing service companies.