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Radon Levels

Radon Levels Map
Disclaimer: It is strongly recommended that all households, schools and office spaces test radon levels individually. The EPA Radon Zone data is not an indicator of individual test results, but a guideline for strategic planning. Toxic radon levels can be found in all counties, regardless of their zone rating. While we make efforts to keep this information up to date, it is derived from third­party sources which may not be accurate or reflect the most current statistics.

User Submitted Radon Levels Across The Country

Alabama(5.88) Alaska(7.24) Arizona(6.84) Arkansas(9.86)
California(5.72) Colorado(9.31) Connecticut(6.93) Delaware(6.24)
Florida(6.95) Georgia(7.18) Idaho(8.79) Illinois(7.44)
Indiana(7.7) Iowa(9.95) Kansas(8.13) Kentucky(9.29)
Louisiana(4.67) Maine(8.12) Maryland(8.89) Massachusetts(7.66)
Michigan(6.65) Minnesota(6.88) Mississippi(9) Missouri(6.8)
Montana(8.03) Nebraska(7.28) Nevada(7.14) New Hampshire(8.94)
New Jersey(6) New Mexico(7.29) New York(7.15) North Carolina(7.84)
North Dakota(9.77) Ohio(8.35) Oklahoma(7.53) Oregon(7.02)
Pennsylvania(9.68) Rhode Island(7.52) South Carolina(7.06) South Dakota(10.21)
Tennessee(7.59) Texas(7.42) Utah(7.96) Vermont(7.35)
Virginia(7.57) Washington(6.81) Washington DC(4) West Virginia(9.48)
Wisconsin(8.43) Wyoming(8.06)

Radon gas can be extremely hazardous to the human body when long term exposure is involved. That is why it is very important that you monitor radon levels in your home or business regularly. If the levels are elevated then you must take action as soon as possible to eliminate the problem. There’s a common misconception that radon mitigation is very costly, but that is simply not true. In fact, the problems that will arise from not taking care of the problem early will be more costly than the removal process – especially when you factor in medical bills.

Radon is the second leading cause of lung cancer, so you can bet there will be plenty of medical bills from long-term exposure. The US Environmental Protection Agency (EPA) and the Surgeon General’s Office estimate that as many as 20,000 lung cancer deaths are caused every year by radon poisoning. In other words, radon can become a serious problem if left unchecked. If you want to know more about radon in general, or you would like to know how to test for radon, visit the appropriate pages here at We have plenty of information on the site to help keep you in-the-know.

Since we’ve already discussed radon basics and testing methods elsewhere, we’re going to explore the different levels of radon. Most people are aware that you need to test for radon regularly, and there are plenty of home testing kits available at local retailers, hardware stores and online. Unfortunately, there is a lack of reference material on the various radon levels that can be returned by such tests. We will cover the various levels individually, and what each one of them mean for your health. We will also briefly touch on the basics of the radon mitigation and removal process.

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What are the Different Radon Levels and What do they Mean?

Radon is measured in Picocuries per liter of air, or pCi/L.

If you’re new to all of this, the numbers can certainly be daunting. Don’t fret, because we’re going to break down each level individually. The chart below compares the risk of cancer to various other risks, as it pertains to each significant radon level. It should be noted that this information only applies to people who have never smoked. The risk increases exponentially if you have smoked and you are also exposed to radon gas.

What Levels are Considered to be "Safe" Living Conditions?

According to the United States EPA, any amount of exposure to Radon gas is unhealthy. However, the EPA has set an action level of 4 pCi/L, which means if the levels in your residence meet or exceed that amount you should take action immediately. The recommended limit of 4 pCi/L is the absolute maximum it should ever be inside a residence. Levels higher than that are exponentially more dangerous in terms of exposure. The risk of lung cancer increases about 16% per every 2.7 pCi/L.

That being said, it is recommended for any and all residences to maintain a level of 2 pCi/L or below. In fact, if the levels in your residence are higher than 0.4 pCi/L you should look into proper Radon mitigation procedures and methods.

The average indoor level of Radon gas is about 1.3 pCi/L. The national average of outside radon levels is approximately 0.4 pCi/L, which is why the number was listed above as a reference point for mitigation. Depending on where you live, the levels outside of your home may be as high as 0.75 pCi/L.

At 0.75 pCi/L, 2 people out of 1,000 would likely get lung cancer if exposed to that level of radon gas over their entire lifetime, provided they never smoked a day in their life. Again, that risk increases significantly where smoking is a factor.

What are Some Symptoms Associated with Radon Exposure?

Unfortunately, there are no short term symptoms associated with radon exposure. Couple that with the fact that radon is colorless, odorless and tasteless and you can see why it's incredibly dangerous. You will not be able to tell whether you are being exposed to elevated radon levels unless you specifically test your residence. The only known and documented symptoms that go along with radon exposure are those also associated with smoking-induced lung cancer. That being said, such symptoms are most likely to appear after years and years of long term exposure. Not that any other symptoms would be welcome. It goes without saying, lung cancer is serious enough.

Radon decays rather quickly, producing small radioactive particles. These particles can be inhaled into the lungs, where they sit before eventually damaging the cells lining the interior. The damaged or cancerous cells can deteriorate to the point of failure. There is also inconclusive evidence of an increased risk of leukemia in adults and children that have been exposed to radon.

All of these numbers are useless without something practical to back them up. Cigarette smoking is the leading cause of lung cancer, and that’s pretty well known. Radon presents a far smaller risk, however it is still the second leading cause of lung cancer in the US. Approximately 15,000 to 20,000 lung cancer deaths each year are due to radon exposure.

There are several different forms of lung cancer one can contract from chronic exposure to radon gas:

Cancers Caused By Radon Exposure

  • squamous cell carcinoma
  • small cell carcinoma
  • adenocarcinoma
  • large cell carcinoma
There are also several respiratory diseases or issues that can be caused by long-term radon exposure:

Radon Related Respiratory Issues

  • emphysema
  • pulmonary fibrosis
  • chronic interstitial pneumonia
  • silicosis
  • respiratory lesions

As previously mentioned, the combination of tobacco smoke and radon exposure increases the risk of cancer exponentially. More than ten percent of radon-related cancer deaths occur in nonsmokers, which means the other 80-90% are smokers.

It was first discovered that radon is associated with lung cancer because underground uranium miners were dying frequently from it. The environment where they spent most of their time was saturated with extremely high levels of radon, so they experienced long-term exposure. In tests done on minors, it was also discovered that other variables played a role in the affect radon had on their lungs such as age, duration of exposure, and the time since the first exposure.

How Do You Test for Radon in a Residence?

We have a very long and informative page that discusses everything you would ever want to know about testing for radon in your home or business. That aside, we'll cover the basics here so that you can get familiar with the idea of radon testing.

There are two different types of radon tests available: long-term or short-term. The short-term tests are designed to be run over a span of 2 to 90 days, whereas the long-term tests are designed to be run for 90 days or longer. The reason for this is because radon levels can be affected by many different variables including the season, temperature and more. Just because your radon levels are low at one point in time does not mean they are not higher at all, and vice versa. Long-term tests are designed to provide an accurate reading for an entire year or timeframe.

It is common practice to start with a couple of short-term tests first, and if the levels read higher than 4 pCi/L to move on to a long-term test. There are DIY radon testing kits available at any local hardware store, retailer or online. If you are not comfortable performing the test yourself you can hire a professional. It is worth noting that some radon mitigation contractors will and can run tests, however you should never assume as such. In some cases you may have to hire a specialist to run the tests and analyze the results, and hire another professional to perform the radon mitigation maintenance on a home or residence – when the levels are elevated, of course.

It can take a while to get the results back for a test, especially when you opt to use a DIY kit. This is because you must first collect air samples in the residence, and then you must mail the samples to a remote lab. The air will be analyzed and the lab will return an in-depth report about the air that was tested. More importantly, they will provide an accurate reading of radon levels in your home. Because there are many things that can affect the outcome of a test, it is wise to run multiple tests in a home.

How to Reduce Radon Levels if they are too High

In the event that radon levels in your residence are found to be elevated, you should take action as soon as possible. There are several ways to mitigate radon gas in a residence, but we recommend hiring a professional contractor to aid in the process. Radon mitigation contractors will generally assess your residence and approach the process appropriately. The type of radon mitigation system that is put into place depends on your location and your home. More importantly, the foundation of any home can greatly affect which method is used.

In houses with a basement, or crawlspace radon is reduced through four different types of soil suction: sub-slab suction, drain tile suction, sump hold suction and block wall suction. Sub-slab suction is actually one of the most common and most effective radon reduction methods. It involves running suction pipes below the floor or foundation directly into crushed rock or soil. The system basically vents out the radon gas before it can travel anywhere else. Most modern homes will be outfitted with a sub-slab system provided the foundation allows for it. The average system costs about $1500 to put into place.

Another method involves a device called a heat recovery ventilator (HRV), or air-to-air heat exchanger. It essentially creates ventilation to the outside by introducing fresh air into a residence, cooling or heating the new air at the same time. HRVs are actually more effective in confined areas like a basement, and must only be used when radon levels are well below 10 pCi/L. Depending on the size of the device HRVs can cost anywhere from $600 all the way up to $1500. Obviously, the more powerful the device the higher the cost.

Additional radon mitigation techniques include the following – effective mitigation levels are also listed where applicable:

You may or may not choose to seal your home better, but it should be noted that this will not reduce existing radon levels. Instead, sealing a home will only make a radon mitigation system more effective and should help prevent future gas from seeping in. It should never be used as a single method in radon reduction strategies. However, a contractor may recommend sealing off gaps and cracks in floors, walls and the foundation. If the radon levels are dangerous and the mitigation system doesn't seem to be helping as well as it should, this may be a suitable solution.

Finally, once a radon mitigation system is in place you must monitor and maintain it. It is an important part of the radon mitigation process even though it’s considered an extra step. If the system ceases to ventilate the radon properly the levels will increase all over again.

Radon in Water

Radon can also enter your residence through the water supply, however there's a much greater risk that it will enter your home through the soil and foundation. Radon in water is generally a problem if you have a private well for your home. If you are concerned that radon may be entering your residence through the water supply there are special tests you can run. While it is possible to get stomach cancer from ingesting radon, it's more likely that you will also contract lung cancer from long-term exposure through a contaminated water supply. This is because you will be inhaling the radon particles while in the shower, drinking from the water or interacting with it in some other way. Therefore, it is still possible to contract one of several forms of lung cancer due to radon from a private water supply.

Water-based radon problems can be easily fixed in one of two ways, through point-of-use or point-of-entry. Point-of-entry involves putting a system in place to filter the radon before it even enters your home. Point-of-use involves placing a granular filter on the faucet or exit point so that the radon can be filtered before it is passed through. The point-of-use based systems are less effective in removing a radon presence completely, because there are several areas and points of entry for a water supply and it's likely that the filtration system will not cover every one of them.

How do You Monitor Radon Levels in Your Home?

One of the most effective ways to monitor radon levels in a residence or business is to install a radon detector. It works almost exactly like a fire alarm or smoke detector. It constantly analyzes and monitors the air for traces of radon gas. If the levels reach a dangerous amount, the detector will sound an alarm. Most radon detectors will also display an approximate level rating. In some cases, a radon detector can return more accurate results than a DIY test, especially one that requires the results to be mailed.

Radon detectors should be handled just like testing kits. In that respect, they should be installed in the lowest level of the residence, and they should be left to sit for at least a month before a reading is taken. In addition, you should refrain from opening windows and doors to the outside as much as possible when you first install the device. Most detectors will simply mount to the wall, and are powered through a regular power outlet or batteries.

Since radon test kits can cost more than $15 and multiple will be necessary it may be a better idea to purchase a detector, which is usually in the range of $100-$150 depending on the model and features. A detector should never be considered the deciding factor when it comes to installing a mitigation system. If radon levels are high, you should have a system installed regardless.

If you would like a bit more information on radon in your area you can visit this US EPA page and select the state where you live. It will take you directly to the contact information for the state radon center in your area.