Indoor Air Quality - Radon: Danger lurking below

Your brand new finished basement has finally been completed. The kids finally have a place to play, the media room has the biggest flat panel on the block, and your new exercise area will help the whole family stay in shape. The sump pump has a battery backup, the walls are air-tight, what could go wrong? If you don't know your home's radon levels, consider that all the time you spend in the basement could be just as damaging to your lungs as sitting in a smoking lounge!

Radon gas is an odorless, invisible radioactive gas that is produced by the natural process of radioactive elements in the ground breaking down.

Here is some interesting information about radon gas:

• Radon is the leading cause of lung cancer among non-smokers.


• Radon is the second leading cause of lung cancer in America and claims about 20,000 lives annually.


• Radon is one of the heaviest gasses present under normal room temperature conditions.


• Radon's most stable isotope, radon-222, has a half-life of about 3.8 days. It decays into polonium-218 through alpha decay.


• Radon can be carried into your home through natural gas (think kitchen: range, oven).

Most folks in Northern Illinois are not aware that they live in a medium to high risk area for radon exposure. See the image below for your area's risk level, (taken from the EPA's radon zonemap Red = "action" levels over 4 pCi/L (pico curies per liter); Orange = moderate risk at 2-4pCi/L; Yellow = low risk at under 2 pCi/L).

The good news is that with some minimal effort, unsafe levels of radon can be detected; and if found, your home can be made safe from radon with minimal investment.

It is important to test your home for radon, as levels vary greatly from home to home, and from season to season; even neighbors can have very different levels of radon. Generally speaking, the highest radon levels will occur when the ground is warm, and the lowest levels when it is frozen. Radon levels can even vary large amounts from week to week, so radon tests that take a longer time to complete (alpha-track counters that take one or more months) generally yield more accurate results.

The Illinois Emergency Management Agency (IEMA) offers Illinois residences free radon test kits. These tests consist of a sponge-like carbon 'collector' that you unwrap and place in a test area for three to 7 days, then wrap back up and send in to a lab for analysis. < UPDATE: The free test kit program was stopped, because two-thirds of the test kits sent out were never used.. A listing of test kits is now available here; the 'Air Chek' brand kit that the state was providing for free is available at a discount for $6.95 >

For those not living in Illinois these tests may be available free or at a discount from your state or local public health & safety agencies, at your local hardware store, or can be purchased online:

For continuous monitoring of radon levels, electronic alpha-track counters that display the radon levels and sound and alarm when high levels are detected are available, but more expensive at over 100$.

Anyone who has sealed air leaks in their home should also be sure to re-test for radon, as reduced air flow can result in increased radon concentrations.

New homes should be built with 'passive' sub-slab depressurization radon mitigation systems, these systems help to vent radon gas from under the home using natural air movement, and generally cost $400-1000 to install during construction. Another advantage to these systems is if radon levels are found to be elevated in the home after construction is completed, they can be easily converted into an 'active' mitigation system by adding a radon mitigation fan to help move the radon gasses away from the home foundation. Note : a licensed radon mitigation specialist must install the fan to meet state requirements.


If you find you have high radon levels in your existing home, some steps can be taken to try and reduce the amount of air that contains radon from coming into your home. The primary way radon enters the home is through ground air infiltration. Putting an air-tight cover over your sump pit and sealing cracks along the floor of your foundation can go a long way to reduce radon levels. Making sure your stove vent runs to the outdoors and being sure to run the vent while cooking can also help to reduce radon levels and other indoor air pollutants.

Adding an active mitigation system to an existing house is usually more expensive and less effective than adding the passive system during construction, and can range in cost from $800-$3000.

Be aware- As of January 1st, 2008; if you have a Radon test performed in your home, you must disclose the results to any future potential buyer, because of a new state Public Act 095-0210 "Illinois Radon Awareness Act". Even if you don't test, you must include a signed statement saying that you don't know of any radon information, and include the pamphlet "Radon Testing Guidelines for Real Estate Transactions".

More radon information:

For simple answers to your Radon questions check out the Take Action on Radon Website (a University of Illinois extension service)