How to respond to your radon levels

Congratulations on taking the first steps to learn about the radon levels around you. This quick guide will help you find out what to do next, based on the readings you’ve received on your device.

Now that you know how many Bq/m3 or pCi/L are inside your home, you also need to know what these numbers mean! Should you be worried? Is it necessary to install a radon pump? Should you just open the window more often?

Some of Airthings’ devices are able to show results just one hour after setting them up. However, it is recommended to measure for at least one full month to get a more comprehensive set of readings. Due to the fluctuating nature of radon, the longer you measure, the more accurate the readings will be.

But first, a bit about radon

Radon exists everywhere, even in the open sea, but radiation only becomes a problem when it starts concentrating. It is easier for radon to accumulate in well-insulated office buildings or homes than in areas that are open or constantly ventilated.

According to the World Health Organization (WHO) on its 2009 Handbook on Indoor Radon, there are over 40 case-control studies that have contributed to understanding the link between radon exposure indoors and lung cancer. These studies have also helped to establish what normal levels of radiation are or, more accurately, those considered acceptable.  

Radon is leading cause of lung cancer among non-smokers. Each country or region is in charge of developing a national plan for mitigation and control of radon gas; these plans are “aimed at minimizing exposure of the population to radon”. The European Union has established some guidelines that take into account the soil conditions.

So, how much is too much?

There are factors that affect indoor radon levels, like weather conditions in your area or the time of the year. In zones far from the equator, there are normally higher levels during the winter than the summer because in the cold weather most people ventilate less. 

The normal radon concentration outdoors is about 10 Bq/m3. The worldwide average indoors is 39 Bq/m3. There might be a room in your home or office with concentrations that are slightly above the average. It is normal to have different levels in different areas and rooms, especially if the ventilation is not the same.

While it is recommended to implement mitigation measures in rooms where levels are much higher than the reference levels, values slightly above average are not as harmful if you spend a little time in there. In other words, if you have a room with an average radon concentration of 350 Bq/m3 but only use the room for storage or pop in once in a while, you will be safe. However, you should always make sure the radon is not seeping into other areas of the building. You can find more information here from a case study about radon toxicity.


What do to next 

Radon particles have a half-life of 3.8 days. This means it’s possible to reduce concentration just with proper ventilation. As ventilation increases, radon concentration will decrease.

In areas where there’s constant ventilation, radon levels will tend to align with normal concentrations outdoors. Try to ventilate and measure for at least a week in a particular room to see if levels get closer to normal outdoor values (~10 Bq/m3).

It is important to do a long-term measure in places where you normally spend a lot of hours like bedrooms or your office. Overall, if concentrations are:

  1. 0 - 49 Bq/m3  (0 - 1.3 pCi/L):  No action necessary.
  2. 49 - 99 Bq/m3 (1.4 - 2.6 pCi/L): Experiment with ventilation and sealing cracks to reduce levels.
  3. 100 Bq/m3 - 299 Bq/m3 (2.7 - 8 pCi/L): Keep measuring. If levels are maintained for more than 3 months, contact a professional radon mitigator.
  4. 300 Bq/m(8.1 pCi/L) and up: Keep measuring. If levels are maintained for more than 1 month, contact a professional radon mitigator.


The Radon and Health Fact sheet from the WHO states that:


“Radon levels in existing homes can be reduced by increasing under-floor ventilation, installing a radon sump system in the basement or under a solid floor, avoiding the passage of radon from the basement into living rooms, sealing floors and walls, and improving the ventilation of the house. Passive systems of mitigation have been shown to be capable of reducing indoor radon levels by more than 50%. When radon ventilation fans are added radon levels can even be reduced further.”


National agencies normally recommend the most cost-efficient methods to reduce radon, should levels not be reduced by simple ventilation. If the problem is severe, many countries offer financial support or tax credits to help homeowners with the installation of active mitigation methods.

 There is usually a list of certified radon professionals in each country that can help you reduce the concentration of radon. Many national agencies provide this directorate or point you in the right direction to find the person or business who can help you. Search for “radon” on your government website, otherwise turn to the local Health and Safety authorities for more information and help.

Acceptable levels according to your location

The values presented in this document are taken from governmental agencies and official national organizations that regulate radon and air quality. Most of the measures were taken in periods of one year or more.

While most of the countries stick to values suggested by international organizations, like the WHO, each country makes exceptions based on local soil conditions and other industry regulations.

Most countries set different action levels for homes and offices, the latter being higher than residential ones. The links provided here contain information about action levels for homes; some of them also include workplace information.



Although the effects of radon were first documented as early as 1530 in Europe, the famous “Watras incident” in the U.S in 1984 put radiation regulations on the map. Since then many studies have been carried out to find a correlation between lung cancer and radon exposure.

That’s why recommended values in North America are lower than those recommended by the WHO, and workplace regulations –especially regarding power plant and mine workers– are stricter and more comprehensive than in Europe.



Recommended levels in Canada are set at 200 Bq/m3. Any buildings with higher levels require mitigating actions and, for spaces with levels higher than 600 Bq/m3, these actions must be taken within a year.

If the levels are between 200 Bq/m3 and 600 Bq/m3, mitigation has to happen in less than two years. The Canadian government states that these levels are “based upon current scientific understanding”.

You can visit the radon section of Health Canada’s website to learn more about specific radon regulations and get access to resources that the government of Canada has created for the general public.


The U.S. Environmental Protection Agency (EPA) is the one in charge, among other things, of creating radon laws and regulations. The agency has done a good job at spreading awareness about radon and providing information to the general public.

According to the EPA’s “Home Buyer’s and Seller’s Guide to Radon”, almost one in 15 homes in the U.S.A. has radon concentrations above the recommended levels. This guide includes a lot of useful information about radon; you can read it here.

They have created a very useful chart that compares the risks of smokers vs. non-smokers with the likelihood of getting lung cancer. You can see it here. Acceptable levels in this country are between 2 and 4 pCi/L.



The European Environment and Health Information System (ENHIS) has surveyed 13 countries in Europe and recommends action levels between 200 Bq/m3 and 400 Bq/m3. There are specific guidelines for each country since the type of soil varies both per country and within each region.

ENHIS states in its 2009 report, which you can read here, that “there are clearly huge differences between countries in terms of exposure to radon in dwellings in Europe”. That is why it is important to pay attention to local concentration levels and that way you can also learn if you live in an area that is considered a “risk zone”.

Germany, Poland, the Netherlands and the UK will have lower levels, in average, than Austria, Finland, Sweden or Czechia. However, the downside of using geographical expectations is that if your home is built over sedimentary soils, radon can over-concentrate if ventilation is poor. If you live in a high-risk zone you can have low levels in your home, if you live in a low-risk zone you can have high levels in your home. This is why every single home needs to be tested.


According to the Norwegian Radiation Protection Authority, “Norway is among the countries in the world where indoor radon reaches its highest concentrations”. About 10% of all buildings in Norway have a concentration higher than the recommended 100 Bq/m3.

Current legislations set the limit at 200 Bq/m3 for schools, new buildings, and rented accommodation. The action level for reduction is set at 100 Bq/m3, in accordance with WHO’s recommendations. 

The government has discussed targets to reduce and control radon in Norway; existing buildings in the country “with indoor radon concentrations exceeding 200 Bq/m3 must be considerably reduced by 2020”. For more specific measures and procedures, you can check the official guide here.


Because of the type of soil, most homes in France have an average indoor concentration of 90 Bq/m3. Even so, there are about 300,000 buildings with concentrations over 400 Bq/m3 and about 60,000 with levels higher than 1000 Bq/m3.

Regions that are rich in granite, like Bretagne and Massif-Central, have the highest concentrations in the country. You can consult France’s radon map here. New buildings are expected to have levels of 200 Bq/m3 and below. However, because of the type of soil, the government only recommends taking corrective actions for levels higher than 400 Bq/m3.


According to radon mapping in Germany, between 10% and 50% of buildings in the country have radon levels over 100 Bq/m3, for which actions are required. If levels are above 1000 Bq/m3, mitigation has to be implemented within a period of three years. 

All new buildings are expected to have concentrations below 100 Bq/m3. The Federal Office for Radiation Protection recommends ventilating frequently and intensively and sealing cellar doors and cracks or gaps in areas that are in direct contact with the soil.



The agency for Environmental Quality in Italian Urban Areas states that more than 10% of all cases of lung cancer in Italy are related to radon. The country follows its own guidelines, as well as those of the European Union, and there are public and private companies that help people measure their indoor air quality. 

The radon regulations of the government of Italy include only schools and offices, where radon levels need to be reduced if they are above 500 Bq/m3. Households are excluded therefore homeowners are solely responsible for measuring indoor radon levels.



According to the Council for Nuclear Safety of Spain, laws regarding exposure to radon were re-established in 2006. The government of Spain recommends following EU guidelines and introducing corrective measures for concentrations above 400 Bq/m3 in existing buildings.

Laws previous to 1993 required actions at 600 Bq/m3. After Spain became part of the EU action levels were changed to follow WHO’s recommended levels and EU guidelines. The official report is available here, in Spanish.

The project to create a comprehensive radon map of Spain was finished in 2013, and it is available here. The goal of this project was identifying zones and regions that were most likely to have high concentrations of radon to reduce exposure as much as possible.

United Kingdom

The Department of Public Health England has created a very useful interactive radon map where you can see specific concentrations in each area of the UK. Take a look at the map here.

As of 2010, the UK's Health Protection Agency set 100 Bq/m3 as a target level “because research published since 1990 has given scientists a greater understanding of the risks to our health of exposure to radon below 200 Bq/m3”.

Actions are recommended for levels above of 200 Bq/m3. You can find a pricing list to know the costs of active mitigation methods, should your levels be too high. You can consult them here.

Hopefully, your radon levels will be within the recommended values. Don’t forget to keep ventilating and, once again, thank you for purchasing an Airthings detector.

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