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Indoor Air Quality and Radon

Indoor Air Quality: Radon
Allergy sufferers are particularly affected by what is in their indoor air. Allergens like dust mites, pollen, mold spores, pet dander, along with other allergy triggers like artificial fragrances, fumes from chemical cleaners, and off-gassing from carpet adhesives, can combine to make indoor air in the home very unhealthy.

Whether or not one suffers from allergies, however, it's important to know that what's found in indoor air does in fact affect on our health - even if we can't smell it, see it, or taste it. This is the case with radon, and its effects can be deadly.

Radon is the leading cause of lung cancer in non-smokers. Radon gas is colorless and odorless; the only way to detect it is to specifically test for it. Because it comes mostly from the soil beneath the house and it exists in pockets, there's no way to predict whether it could be polluting your indoor air until you test for it.

The good news is that if excess radon concentrations are present in your home, the problem can be fixed, and at not too great a cost. Below we explore what radon is, how to test for it, and how to prevent it from polluting your indoor air and endangering your family.

What is Radon?

Radon is an odorless, tasteless, invisible gas that comes from the decay of naturally occurring uranium in soil and water. It is found in outdoor air and in buildings of all kinds. Radon is a form of ionizing radiation, and "a proven carcinogen," as described by theEnvironmental Protection Agency (EPA).

As mentioned, radon is the second leading cause of lung cancer, even among those who have never smoked. Smokers who are exposed to radon are particularly at risk for lung cancer because of the synergistic effects of radon and smoking.

Radon is everywhere. The average American home contains radon at a concentration of 1.3 pCi/L (pico Curies per Liter). It's important to note that this measurement is the source of the estimated 20,000 lung cancer deaths per year attributable to radon exposure. Therefore, although the "must-fix-it" concentration of radon is 4 pCi/L or higher, the EPA still recommends that Americans consider fixing their homes if concentrations range between 2 pCi/L and 4 pCi/L. Compare this to the outdoors, which has a an average concentration of 0.4 pCi/L.

Consider this statement, from the EPA's page on radon:

"Unfortunately, many Americans presume that because the action level is 4 pCi/L, a radon level of less than 4 pCi/L is 'safe.' This perception is altogether too common in the residential real estate market. In managing any risk, we should be concerned with the greatest risk. For most Americans, their greatest exposure to radon is in their homes; especially in rooms that are below grade (e.g., basements), rooms that are in contact with the ground and those rooms immediately above them."

How Does Radon Get Inside My House?

Radon in the homeRadon is produced by the breakdown of uranium that's present in rock, soil, and water. Radon gas gets into your home either through the soil beneath the home or through drinking water, and in some instances through rock likegranite that's inside your home.

The soil beneath the house is the main source of radon in people's homes. Because the air pressure in the home is less than that of the soil around the home's foundation, homes actually act like vacuum cleaners and "suck" radon gas into indoor air through foundation cracks and other openings. This is by far the most common and biggest source of radon exposure.

Well water may also release radon gas into the home, however. When water is used for showers, washing dishes, or other household purposes, radon can be released into your indoor environment.

How to Test for Radon

EPA Radon Protocal Guidebook"While basic types of tests and methods will be outlined below, consult the EPA's Protocols for Radon and Radon Decay Product Measurements in Homes for thorough details.

Short-Term Radon TestYou can purchase inexpensive kits that will test radon levels in your home. The Kansas State University's National Radon Program Services is one online source for various types of radon test kits.

There are two main types of radon tests, short-term tests and long-term tests. Short-terms tests are the fastest way to see if your home contains high radon levels, and are recommended by the EPA for initial assessment of radon levels. Testing with a short-term radon test kit takes at least 48 hours, but sometimes longer.

To use a short-term radon test kit:

  • Place the test in the lowest lived-in level of the home.
  • Close windows and outside doors, and leave them closed as much as possible during the testing period.
  • If testing for two or three days, keep windows and doors closed for 12 hours before beginning the test.
  • Don't conduct the test during severe storms or unusually high winds.

Although short-term tests can identify a radon problem, radon levels in a home vary widely, even from day to day, due to fluctuations in weather conditions and the operation of fireplaces and furnaces, as well as the amount of outside air that's circulating indoors. Thus, a short-term test lacks accuracy when it comes to determining your year-round radon exposure average.

Long-Term Radon TestLong-term radon tests give homeowners a better idea of their year-long average radon exposure. Long-term tests remain in the home for 90 days. Again, because radon levels vary by season, the longer a long-term tests is used, the more accurate its measure of average radon concentrations in the home. If long-term tests show an average higher than 4 pCi/L, the EPA recommends that action definitely be taken to correct the problem.

Radon Test DevicesEPA Radon TestsIn addition to short-term or long-term tests, radon testing devices fall into two categories: active devices and passive devices.

Active devices need power to function, and are quite sophisticated in how they measure. For instance, some active devices can provide data on the range of variation within the testing period or can detect and minimize interference in the test. These types of devices usually require a trained professional to operate them.

Passive devices, on the other hand, are designed for use by homeowners themselves, who send the device to a laboratory after the testing period. The lab analyzes and reports radon levels. Passive devices do not need power to function. Types include charcoal canisters, alpha track detectors, and charcoal liquid scintillation detectors. Note that charcoal kits are prone to interference by humid conditions.

How to Fix a Radon Problem in Your Home

If tests and follow-up tests confirm high radon levels in your home, there are ways to remediate the problem. The Consumer's Guide to Radon Reduction offers comprehensive information about how high radon levels may be mediated. Below is some basic information:

  • Radon mediation methods are effective, often able to reduce radon levels by 99 percent.
  • The EPA recommends using a qualified radon mitigation contractor fix your home. Fixing radon problems requires particular technical knowledge and specialized skills. Your state radon office is a good place to find certified radon contractors.
  • Radon reduction techniques include both systems that prevent radon from entering the home and systems that reduce radon levels after it has entered the home.
  • The type of foundation your home has affects which type of radon mediation method will be best for your home.
  • In addition to whole-house systems, other measures to reduce radon levels and make mediation methods most efficient include sealing cracks and other openings in the foundation.

Air Purifiers and Radon

HEPA Air Purifiers and RadonThe function of air purifiers is to make your home's air cleaner, ultimately to give you and your family better air to breathe. While air purifiers are routinely recommended to allergy sufferers for filtering the air of particles like pollen, pet dander, mold spores, dust mite allergen, and the like, air purifiers can also help purify your indoor air of toxic chemicals and gases, including radon.

But while air purifiers fitted with activated carbon filters are able to trap some ambient radon, it's important to note that, as stated on their own site, the "EPA does not recommend air cleaning to reduce the health risks associated with radon and the decay products of radon gas, which are called 'radon progeny.'"


"The Agency recommends the use of source control technologies to prevent radon from entering residential structures. The most effective radon control technique is active soil depressurization (ASD). An ASD system uses an electric fan to minimize radon entry by drawing air from under the slab/floor and venting it to the outside above the building's roofline. Another, less effective technique installed during construction is a passive radon reduction system, also known as radon-resistant new construction (RRNC). RRNC systems are 'dual-purpose' systems. They typically do not have a fan, but if subsequent testing indicates an elevated radon level, a fan can be installed and the RRNC system will become, in effect, an ASD system."

Additional Resources on Indoor Air Quality and Radon

EPA Map of Radon Zones
Radon Resistant New Construction
Radon Hotlines and Information Sources
Indoor Air Quality
Indoor Air Quality and Indoor Air Pollution
Five Steps to Cleaner, Healthier Indoor Air