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                                                                                Frequently Asked Questions

When was radon in residences first discovered?

In 1984, Stanley Watras, whose body was contaminated with radon, repeatedly set off radiation monitoring alarms on his way in to the Limmerick nuclear plant construction site, where he worked for Bechtel Corp.

How could this happen?

The nuclear plant was under construction and had not begun producing electricity, which is the only way a measurement of radiation from the plant itself would've been possible.

What was the Radiation Source?

When technicians measured the radiation levels in the Berks County, Pa. home of Stanley & Dianne Watras in 1984 around Christmas, they did not believe the test results which measured 2700 pCi/L (675 times the action level), a now known risk to the Watras family's heath, equivalent to each of them smoking 280  packs of cigarettes per day.

Were the high radon measurements common?

Not only were the readings higher than they had ever seen, but they also were well beyond what scientists had thought was possible in a residence. "It surprised the heck out of everybody because nobody had ever seen anything that high, " said Bill Belanger, a radiation specialist with U.S. Environmental Protection Agency.

Were the record radon levels  accurate?

The numbers turned out to be accurate. The Watras' split-level home on Indian Lane in Colebrookdale Township had the highest levels of naturally occurring radiation ever recorded in a home in the United States.

What action occurred?

Stanley Watras, 34, quickly moved his family out of the house, where they had lived for a year. Meanwhile, state officials set about testing other homes in the area to determine whether they were dangerously radioactive. The radon levels in the Watras home were about 675 times the maximum level permitted in a uranium mine.

Were there other high radon areas?

It was later discovered that many of the Berks County homes were more contaminated than several hundred houses surrounding an old uranium mill in Canonsburg, Washington County, Pa. The Berks County radon levels were also higher than those at houses at Grand Junction, Co. that were built on radioactive waste from uranium milling.

What is the health risk?

The levels of a potentially dangerous radioactive gas called radon, which is emitted by trace amounts of uranium beneath the Earth's surface, were so high that, according to statistics in a 1984 report prepared for Congress, if the Watras’ and their two young sons had lived in the house for just a few more years, they probably would have developed lung cancer.

How common is uranium?

Uranium, the source of radon in the Watras home and millions of others throughout the United States is known to be concentrated in the soil. Uranium is more common in the earth than silver and gold.

What are the characteristics of uranium?

Traces of the radioactive mineral can be found in all rock, especially granite. By its nature, uranium is in a constant state of decay, breaking down into a variety of radioactive substances, including radon, a colorless, odorless and tasteless gas.

What's the harm?

Radon, which can seep into a home through cracks or holes in its foundation, is not necessarily hazardous to humans, but radon decays into highly dangerous radioactive particles, which can lodge in the lungs when inhaled.

Are there studies of the effects on health?

Studies of miners show that these particles, known as radon daughters or progeny, can cause lung cancer. The debilitating disease, usually fatal, can take anywhere from five to 20 years to develop and does not usually appear until after the age of 40.

What exactly is radon?

Radon is a colorless, odorless and tasteless radioactive gas found in homes throughout the United States. Radon is a naturally occurring gas, which emanates from soil, rock and water and gets into the air you breathe. Radon gas comes from the naturally occurring uranium in the soil. In the uranium (U-238) decay series, radon (Rn-222), which emanates from the decay of radium (Ra-226) is the only gaseous element.  Radon gas takes the path of least resistance up through the ground and if the radon source is near a home’s foundation, it will enter the house due to negative air pressure in the home caused by normal house ventilation. The air pressure is lower above a foundation floor than it is beneath it due to mechanical systems such as furnaces, water heaters, gas clothes dryers, bathroom vent fans or due to something as simple as the opening and closing of doors and windows. Individually, or combining a few of these elements, will create a vacuum effect, which will literally suck the radon gas into your home. It enters homes through floor cracks, cold-joints, control cuts, sump pits and any other openings in a foundation or crawlspace. In closed house conditions, the radon gas can maintain elevated levels in your home.

What does radon do?  

Radon is classified as a Class A (Group1) carcinogen which is a substance that can cause changes in cells that can lead to cancer in humans. Inhalation is the exposure pathway. Once in the lungs, residual radon decays rapidly into other decay products that are responsible for lung cell damage which may lead to the development of lung cancer. It has been estimated that exposure to these decay products or progeny causes between 15,000 and 22,000 lung cancer deaths per year. No cancers other than lung cancer have been attributed to radon.

How do you test for radon? 

Radon testing is performed over 2 or more days using a radon test kit or an electronic continuous radon monitor. In Illinois, radon measurement (testing) companies are licensed and regulated through the Illinois Emergency Management Agency (I.E.M.A.) Department of Nuclear Safety’s Radon Program (800-325-1245). If testing is performed in conjunction with a real estate transaction in Illinois, you must use an I.E.M.A. licensed testing company. If not, you can purchase test kits from local hardware stores, home-centers, county health departments or via the internet for as little as $5.00.  

What do my results mean? 

The results of your test will be given in pico Curies per Liter, or pCi/L. If a result is above 4.0 pCi/L, it is suggested that the radon level be mitigated (reduced) to a level below 4.0 pCi/L to minimize health risks. The average outdoor level in the United States is 0.4 pCi/L. In an ideal situation after mitigating, your home could be close to that level. You would then be no worse off being in your home than outside. While achieving outdoor levels is not always possible, all homes can be mitigated to a level below the action level of 4.0 pCi/L.

How do I fix my home? 

Most mitigation methods utilize a sub-slab depressurization (S.S.D.) system in order to remove or re-route the radon gas. You can’t eliminate the source of radon gas but you can re-route the gas and exhaust it past the highest gutter line or eave of your home, where the gas will dissipate and do no harm. Sealing of all radon entry points with caulks, expanding foam sealants, lids or covers is the first step. Secondly, a single hole (if sub-slab material is permeable) or a series of holes (if sub-slab material is non-permeable such as dirt, clay or sand) are drilled/cored through the concrete floor to expose the sub-slab material. Permeable sub-slab material such as gravel or loose fill or combinations of the two are considered ideal for S.S.D. systems, since the suction applied to the excavated hole can reach beyond the suction point to the opposite perimeter of the house foundation. A single suction point typically cored next to the foundation's footing is usually all that is necessary to achieve the desired results. The sub-slab material is excavated/removed from beneath the cored hole in order to create a suction pit or depressurization chamber. Plastic pvc pipe is routed from the excavated hole to where a fan is installed. The fan’s exhaust is then routed to a point at least as high as the highest gutter line of any roof line on the house. Sometimes that necessitates installing the fan on the outside of the house and sometimes the attic space of an attached garage or the house is a possible location. The roof line and /or the basement layout will determine the fan placement. When dealing with other foundation types such as crawlspaces that don’t have concrete floors or foundation walls made of hollow block or fieldstone, the systems are more labor intensive and costly. Suction on crawlspaces is drawn from beneath a newly installed plastic membrane (simulating a floor), which is anchored to the foundation wall. The system utilized in this instance is known as a sub-membrane depressurization (S.M.D.) system. Hollow block foundation walls are sealed at the top openings and suction (via block-wall depressurization or B.W.D.) is drawn from the interior sides of all accessible exterior walls. Fieldstone walls usually allow radon entry through the actual wall itself and suction from beyond the wall is typically the method of treatment.  While you can install a radon mitigation system yourself, it is typically easier, more cost effective, and less time consuming to utilize the services of a mitigation professional. 

How do I confirm my system works? 

24 hours after the activation of your mitigation system, a post-mitigation test can be performed. Depending on how you tested, you will know how effective your system is in a very short time. From the time the system is installed and activated, you could know within 48 hours what your radon level is. If the results are not below 4.0 pCi/L (or below a pre-mitigation level already below 4.0 pCi/L), you can demand additional mitigation. Any reputable licensed mitigation company will guarantee in writing a reduction below 4.0 pCi/L (or below a pre-mitigation level already below 4.0 pCi/L) and will return to perform additional work if necessary to achieve the required level at no added expense to you or your buyer. 

Why do some companies use pvc pipe for exhaust in lieu of aluminum downspout?

Some companies claim that pvc pipe is a better option than aluminum downspout for a system's exterior exhaust. They make claims that: pvc pipe exhaust is quieter with tighter joint connections; pvc pipe can be custom painted to match house colors; pvc pipe is better at withstanding exhaust condensation freezing in extreme winter conditions due to the thicker pipe wall thickness; etc. These claims are nothing more than excuses for using cheaper pvc pipe. Timmit Radon Systems Inc does not utilize pvc pipe for an exterior system's exhaust but rather installs a system exhaust consisting of 3" x 4" aluminum downspout instead. A properly designed & installed radon mitigation system addresses most of the above claims including what is commonly referred to as an ice dam (freezing of exhaust condensation). In fact, we are so confident in our systems that we stand behind them with a full lifetime system warranty. There is no appreciable difference in noise level between pvc pipe & aluminum downspout, since the fan is isolated from both the inlet piping and outlet piping or downspout by rubber couplings, which also act as vibration isolators. While pvc pipe can be custom painted, most installers will charge extra for painting and if the pvc pipe isn't properly primed, the paint won't adhere for long.  Aluminum downspout is available factory painted in many colors at no extra charge to match existing soffit, gutter or siding colors on a house. Since the interior of the pipe is open to outside air, there is no functional difference between pvc pipe and aluminum downspout in any weather conditions, including extreme winter conditions if the system is designed & installed properly. While it would be easier and cheaper for us to use pvc pipe, we use aluminum downspout to meet the aesthetic requirements in today's demanding real estate market. In fact, since business inception in 1996, we've treated EVERY radon mitigation system as if it were being installed in our own home and we will not lower our standards by utilizing pvc pipe for an exterior system's exhaust. Using aluminum downspout to match existing soffit, gutter or siding colors on a house requires extra time, effort and cost that most companies aren't willing to absorb. Instead, companies will try to convince the client that it's better to have the pvc pipe exhaust for the prevention of condensation freeze-up (a false claim) which can happen in extreme winter weather conditions, regardless of the utilized exhaust material. Condensation can occur in any system exhaust (pvc pipe or aluminum downspout) and is caused by warm moist interior air being pumped to the outside, when the outside temperature is significantly cooler.  All properly designed radon systems will drain away any condensation that occurs within the system, along with rain or snow that enters the system under normal conditions. Under extreme winter cold conditions, the warm moist air being exhausted can freeze prior to exiting the top of the exhaust and may form an ice dam. This is caused by the extremely cold air entering the system from the open end and the airflow from the system not being sufficient to exhaust the warm air before it freezes. The ability of the system to exhaust the air under extreme cold conditions is a function of the total system design and is not strictly dependent on exhaust duct material whether it's pvc pipe or aluminum downspout. System design characteristics such as the diameter of the suction pipe, the fan size, the location of the exhaust and length of the exhaust pipe or downspout all affect airflow. Timmit Radon Systems custom designs every radon mitigation system we install, so that it will work properly in all weather, be aesthetically pleasing and meet the requirements established by the Illinois Emergency Management Agency Radon Program.  


Learn more about radon from these sites: 

United States Environmental Protection Agency Radon 


 Illinois Radon Zone Map 


 Home Buyer/Seller Guide 


Cancer Survivors Against Radon

United States Surgeon General

American Association of Radon Scientists and Technologists

Illinois Emergency Management Agency

United States Department of Health and Human Services

American Lung Association