Frequently Asked Questions
about Radon

WHAT IS RADON, AND IS IT DANGEROUS?

Radon is an odorless, colorless, tasteless gas that is produced by the natural decay of uranium and radium in the soil. Since radon is a gas, it can easily enter homes and other buildings. In outdoor air, radon is diluted to very low levels. Inside of homes, radon may become trapped and buildup to dangerous levels. The United States Environmental Protection Agency (EPA) recommends that all homes be tested for radon gas.

Exposure to radon increases your risk of developing lung cancer. It is among the leading causes of lung cancer deaths in the United States, in fact, second only to smoking. The EPA estimates that 14,000 people in the United States die each year from lung cancer due to radon exposure. The EPA recommends that if your home has annual radon concentrations at or above their guideline of 4 picocuries per liter (pCi/l) steps should be taken to reduce the radon level to below 4 pCi/l.

DO MANY HOMES HAVE HIGH LEVELS OF RADON?

The EPA estimates that one out of sixteen homes in the U.S. has radon levels above their radon guideline. In general, homes in the Midwest are much more likely to have high radon levels.

WHY DO MINNESOTA HOMES HAVE MORE RADON?

One reason is we build most of our homes with basements. Since radon is found in the soil, homes with basements are more likely to have high radon levels. The soil in our state contains widespread low-grade uranium and radium. Approximately one out of every three homes in Minnesota has radon levels above 4 pCi/l. As a result, the Minnesota Department of Health (MDH) recommends that all homes in our state be tested for radon gas.

HOW DOES RADON ENTER MY HOME?

Radon can enter a home anywhere there is an opening between the home and the soil as well as through solid material. These openings include dirt floor crawl spaces, cracks in slab-on-grade floors, and concrete block walls. As air is used or exhausted from the home, this "lost" air creates a vacuum (suction) in the home which then pulls in air from the outside. Some of this outside air comes from the soil, which may contain high levels of radon. Some causes of home vacuum are:

• Heated air rising inside the home (stack effect).
• Wind blowing past a home (downwind draft effect).
• Air being used by fireplaces, wood stoves, and furnaces (vacuum effect).
• Air being vented to the outside by clothes dryers and exhaust fans in bathrooms, kitchens, or attics (vacuum effect).

The main routes for radon to enter a home are shown below. For most Minnesota homes, well water is not a major source of radon gas.

MAJOR RADON ENTRY ROUTES

• A. Cracks in concrete slabs.
• B. Spaces behind brick veneer walls that rest on uncapped hollow-block foundations.
• C. Pores and cracks in concrete blocks.
• D. Floor-wall joints.
• E. Exposed soil, as in a sump or crawl space.
• F. Weeping (drain) tile, if drained to open sump.
• G. Mortar joints.
• H. Loose fitting pipe penetrations.
• I. Open tops of block walls.
• J. Building materials, such as brick, concrete, rock.

HOW CAN I CHECK MY HOME FOR RADON?

The only way to know the radon level in your home is to test your home. Each home is different, and a neighbor's radon results can't be used to determine if your home has a problem. Homeowners can purchase simple, low-cost radon detectors for use in their homes. The two most common types of radon detectors are long-term (alpha track or electret ion) and short-term (charcoal canisters).

The MDH recommends the use of a long-term detector to check the radon level in your home. If you use a long-term detector, the MDH also recommends that you:

• Buy an EPA listed detector. If possible, leave it in place for three months to one year (longer is better).
• Be sure to follow any directions provided by the manufacturer.
• Place the detector in lowest livable area of home (usually basement).
• Put the detector in a general use area such as a bedroom, family room or office.
• Do not place the detector in the crawl space, furnace room, laundry room or other enclosed areas.
• If possible, put the detector 3 to 5 feet off the floor (in your breathing zone).

Short-term detectors can also be used. However, these detectors may give you a less accurate picture of the long-term average radon level.

If a short-term detector is used, MDH recommends that you:

• Buy an EPA listed detector.
• Close all doors and windows at least 12 hours before the test begins and keep closed throughout the test period.
• Place the detector in the lowest livable level of the home (usually the basement).
• Be sure to follow any special directions provided by the manufacturer.
• Put the detector in a general use area such as a bedroom, family room or office. Do not place the detector in the crawl space, furnace room, laundry room, or other enclosed areas.
• If possible, put the detector 3 to 5 feet off the floor (in your breathing zone).
• If possible, expose your short-term detector for 5 to 7 days unless the manufacturer recommends a shorter time.
• Do not test for radon during extreme weather conditions (such as strong winds, heavy rain, or the passage of a storm front with a drop in barometric pressure).
• Do not operate bathroom or kitchen exhaust fans or nonessential appliances such as fireplace, clothes dryer.

Both long-term and short-term radon test kits can be purchased from the Scott County Environmental Health Office. You may find and print our online form for this purpose.

HOW CAN I PROTECT MY HOME AGAINST RADON?

There are three basic strategies to reduce your exposure to radon.

Avoidance: Radon is only dangerous if you breathe it. If you avoid the areas in your home that have high radon concentrations, then you decrease your risk. Since the major source of radon in Minnesota homes is the soil, the highest levels of radon are often in the lowest levels of your home that have soil contact (usually the basement).

Seal Your Home: Radon gas can enter a home anywhere there is an opening between the soil and the home. Some of these openings are very obvious such as a dirt crawl space. Others are not as obvious, such as openings hidden within a finished wall. Sealing entry routes helps to keep radon out of your home. Since it is difficult to reduce radon levels alone, this technique should be combined with other steps to be effective.

Reducing the House Vacuum: Your home expels air through many activities including burning fuel (furnaces, boilers, water heaters, and fireplaces), and exhausting air to the outside (clothes dryers, bathroom fans, and other house fans). When your home uses air it has to be replaced with "new" air; some of this replacement air comes from the soil. Increasing the ventilation in your home decreases the amount of air that comes from the soil. By decreasing the air coming from the soil, you may reduce your radon level.
Steps to increase your home's ventilation include:

• Open windows. This works, but it is not a practical year-round solution.
• Install vents in your crawl space. Care should be taken to prevent plumbing from freezing.
• Install a combustion air supply to your furnace or furnace room.
• Check your existing combustion air supplies for blockage.
• Adjust your forced air heating system or mechanical ventilator to provide more air to the lowest level of your home.
• If you use ventilation to lower your home's radon level, do not use a continuously running exhaust fan to remove air from your basement. This may increase the radon level in your home.
• Continue normal use of your home's other exhaust fans, for mechanical ventilation, moisture control, and odor control.

DOES SMOKING INCREASE MY HEALTH RISKS?

Your family's risk of developing lung cancer from radon depends on several factors, including the average annual level of radon in your home and the amount of time you spend there. The longer your exposure to radon, the greater the risk. The risk is much greater for smokers. Smoking combined with radon exposure greatly increases your risk of lung cancer. Until you can reduce the radon level in your home, do not smoke in the home and ask other people not to smoke while in your home.

WHERE CAN I GET FURTHER INFORMATION?

This web page brochure covers only basic information about radon. Many more publications are available from the Minnesota Department of Health, and several of these discuss issues related to radon, including:

• radon testing companies
• new construction
• real estate and testing
• do-it-yourself radon reduction
• radon reduction methods
• radon reduction companies
• radon testing in schools

For more information on Radon, contact:

Scott County Environmental Health

952-496-8652
952-496-8787 (24-hour information line)
gboe@co.scott.mn.us

Minnesota Department of Health
Indoor Air Quality Program
(651) 215-0909
(800) 798-9050


If you have a disability and require this document in another format, call (651) 215-0909. For people with hearing impairments and TDD users: the telephone numbers for the Minnesota Relay Service are (612) 297-5454 or call toll free (800) 627-3529. TDD Environmental Health: (612) 215-0707.