Radon Overview

Does your household water come from a well? If so, your water probably has radon gas. Radon gas is normally found in all well water. Bedrock wells typically have much higher radon concentrations than dug or point wells.

WHAT IS RADON?

Radon is a colorless, odorless, tasteless, naturally occurring radioactive gas produced from the decay of the element radium, which occurs naturally in rocks and soil worldwide. Radon gas can dissolve in groundwater and later be released into the air during such normal household activities as showering, dishwashing and doing laundry. When radon accumulates in indoor air it can pose an increased health risk, primarily, lung cancer.

RADON PATHWAYS INTO YOUR HOME

Radon can enter a home via at least three common pathways:

· Migration (up from the soil) into the basement through cracks and/or other openings in the foundation.

· Release of dissolved radon gas from the household on-site water supply.

· Release from building materials such as a granite block foundation, some fireplace materials, and floor or wall tiles.

Although there are some exceptions, in general, the migration of radon up from the soil contributes the largest percent of radon found in the average home. Radon from a groundwater type water supply source, particularly a bedrock well (also known as an artesian or drilled well), contributes the next largest percentage of radon in the home. The radon contributed from building materials is typically very small. DES recommends that the two predominant pathways should be evaluated and that initial action to reduce radon exposure should target the pathway that contributes the largest percentage of risk to occupants.

HEALTH EFFECTS

The primary risk pathway from exposure to radon gas is through inhalation of radon-laden air in a home. Studies indicate that high levels of radon gas in the air increase the risk of lung cancer. An additional health risk is associated with the ingestion of the radon that remains dissolved in the water and is consumed. On average, this latter risk is substantially lower than that associated with inhalation. The risk from radon in water is relatively high when compared to other drinking water contaminants. For more health risk information concerning radon in air and water call the DES Health Risk Assessment Program at (603) 271-4664 or go to their website to see the health related fact sheet on radon at www.des.state.nh.us/EOH/Radon/RadonQ&A.doc

HOW MUCH RADON IS TOO MUCH?

Radon in Indoor Air The U.S. Environmental Protection Agency (EPA) has set an advisory "action level" of 4 pCi/L for radon gas in indoor air. While not a mandated health standard, this level is a guideline for people to use in assessing the seriousness of their exposure to airborne radon. Concentrations noticeably lower than 4 pCi/L are desirable.

TESTING FOR RADON

DES recommends that both the interior air of a home and that private well water supplies should be tested for radon.

Testing Water for Radon - A test for radon gas in drinking water requires approximately two weeks for processing, requires a special sample bottle, and costs $20 (2005) A sample container for the radon water test may be obtained from the DES Laboratory by calling 603-271-3445/3446. Many independent laboratories also provide testing for radon in water. Water testing can be done at any time of the year. If the well/water system has not been in regular use, the entire system should be flushed for at least 20 minutes to ensure that fresh water is captured in the sample container. "Old" water will have a lower radon concentration due to radon's half-life of approximately 3.6 days.

A review of PWS data shows that radon concentrations in water may vary substantially from one test to another due to many reasons including the level of saturated soil above the rock, atmospheric pressure, prior well pumping and other factors. DES recommends at least two radon tests (at least one month apart when possible) be processed before determining the average radon concentration in water.