What Is A Safe Radon Level & How Levels Affect Health

Radon is produced by the decay of uranium in soil, rock, and water. It is an odorless, invisible gas that can seep into any building structure. It enters the home through cracks in the foundation or concrete slab. Radon gas levels can be low enough to cause no harm, or high enough to be a serious health risk.

But what levels of radon are considered safe? Actually, the only safe level of radon is zero. Any presence of radon gas in your home increases the chances of lung cancer. However, achieving zero radon level is not possible. Hence what you can do is mitigate radon as much as possible.

While there are no safe levels of radon, there are certain ‘acceptable levels’. Radon levels are considered acceptable if they are below 2 pCi/L. Mitigation systems should be installed if the levels exceed 4pCi/L, and corrective measures are to be taken if it is between 4 to 2 pCi/L.

The acceptable level of radon in different countries

Radon is present globally. However, in the USA, the average indoor level of radon is 1.3 pCi/L inclusive of hot spots. In Europe and Asia, it is 0.6 to 0.8 pCi/L. Here is the list of countries that consider radon a threat and the acceptable levels they recommend;

CountryAcceptable levelDangerous level
USA2 pCi/L4 pCi/L and above
Canada5.405 pCi/L16.2 pCi/L and above
United Kingdom2.7 pCi/L5.405 pCi/L and above
Norway2.7 pCi/L5.405 pCi/L and above
France5.4 pCi/L10.8 pCi/L and above
Germany2.7 pCi/L27 pCi/L and above
Italy2.7 pCi/L13.5 pCi/L and above
Spain2.7 pCi/L10.8 pCi/L and above
Acceptable radon levels by Source

As you can see from the above table, the USA recommends the lowest levels of Radon. This is because many studies in the USA have found a strong correlation between radon and lung cancer than those conducted in many other countries. In fact, the recommended safe levels in the US are less than that recommended by WHO, which is 2.7 pCi/L or 100 Bq/m3.

Do radon levels vary with geography?

Radon levels vary with geography. Radon levels are higher in areas that have more Uranium deposits in the earth.

Radon levels vary from state to state in the US. This is because of the different radium contents in soil and rocks. The following states have more radon in their above-ground climates;

Alaska, South Dakota, Pennsylvania, Ohio, Washington, Kentucky, Montana, and Idaho.

Does elevation affect Radon levels?

Elevation may have an effect on radon levels. In general, the higher an area is, the higher the radon levels are. However, various studies have shown that the risk of lung cancer for people living in higher altitudes is lower than those living below.

How was the safe level of radon determined?

The EPA’s recommended safe level of Radon is based on many epidemiological studies conducted in the USA. Some of these studies found that high radon levels were found to be associated with an increased risk of lung cancer. Based on these conclusions, the EPA set the recommended safe levels of radon to 4 pCi/L.

However, it is important to note that these recommended levels are not based on any scientific study. They are only estimates based on statistical data.

What is the safe level of radon in water?

Radon can enter your home through groundwater as well. Even though radon is present in surface water, the gas will escape into the atmosphere before the water reaches your home. However, if you use well water, it may contain high levels of radon.

Radon levels in water are considered high if they exceed 10000 pCi/L even though the EPA recommends reducing levels if they exceed 4000 pCi/L in community water supplies. But isn’t that 1000s of times more than the recommended levels of radon? This is because, based on many calculations, only 1 pCi/L of the gas is emitted to the indoor air per 10000 pCi/L of radon concentration in groundwater. So water with radon levels 10000 pCi/L increases the indoor radon levels only by 1 pCi/L.

Is it safe to drink water with radon content?

While drinking radon water can cause cancer in internal organs, its chances are very, very low. Therefore, you don’t need to worry about ingesting radon. The risk is mostly associated with inhaling radon gas, and that is the reason why EPA recommends reducing radon levels in the water.

It is best to reduce radon content in water before it reaches your home. This can be achieved by installing a radon removal system in your well. This includes the use of an aeration system or charcoal-based water filters.

Risk levels of radon

The risk of radon causing lung cancer is very high for smokers compared to non-smokers. Smokers are 8 times more likely to get lung cancer from radon exposure than non-smokers. Also, the higher levels of radon your house has, the more the risk of lung cancer. For example, according to EPA, a smoker who lives in a house with 20 pCi/L of radon levels has 26% of dying of lung cancer while this risk is reduced to 6.2% if the radon levels are only 4 pCi/L.

For a radon level of 8 pCi/L, 120 out of 1000 smokers can get lung cancer while for non-smokers it is 15 out of 1000.

Radon levels like 2.4 and 3.6 pCi/L are considered acceptable. However, about 32 to 62 people out of 1000 smokers can still get lung cancer within these levels. When it comes to non-smokers, the numbers are 4 to 7 people per 1000.

How long is long term exposure to radon

It can take anywhere from 5 years to 25 years to develop lung cancer due to radon exposure. A person who smokes and is exposed to high radon levels can get lung cancer faster than a non-smoker exposed to lower radon levels.

Therefore, it is safe to say there is no definite time frame to be called a long-term exposure.


Charles John

A novice DIYer who learns about home ventilation. I am a mechanical engineer and have a basic knowledge of HVAC systems but I learn continuously to make myself the best blogger in that space.

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