Radon Levels
Radon level of 1 pCi/L: is it safe?
Short answer
A radon level of 1 pCi/L is low: it is below the 2 pCi/L point where EPA suggests considering a fix, and a little under the average U.S. home, which EPA puts at about 1.3 pCi/L. It is not zero risk, since no level of radon is safe, but the guidance at this level is to test again sometime in the future rather than to fix.
Next step: pick the right test for your home. Which test to use
Key takeaways
- 1 pCi/L is 25 percent of EPA's 4 pCi/L action level.
- Below EPA's 2 to 4 pCi/L consider-fixing range.
- EPA estimates the average U.S. home at about 1.3 pCi/L; 1 pCi/L is 0.77 times that.
- You may want to test again sometime in the future, and after a renovation or a move to a lower floor.
Where it sits
Is a radon level of 1 pCi/L high?
- About 35 Bq/m3
- 1 pCi/L in becquerels per cubic meter, at about 37 Bq/m3 per pCi/L (calculated).
- 25 percent
- Of EPA's 4 pCi/L action level (calculated).
- 0.77 times
- The U.S. indoor average of about 1.3 pCi/L (calculated).
EPA's risk chart puts the national indoor average, 1.3 , at about 20 lung cancers per 1,000 people who smoked and about 2 per 1,000 who never smoked, over a lifetime of exposure; a level of 1 pCi/L sits between that row and the outdoor average of 0.4 pCi/L. Reducing radon levels below 2 pCi/L is difficult, so a home at 1 pCi/L is already below the level most homes can be brought to with a radon reduction system.
WHO's recommended reference level is 100 , about 2.7 pCi/L, so 1 pCi/L is under it as well. Congress's long-term goal is indoor air no higher than outdoor air, about 0.4 pCi/L.
Where 1 pCi/L sits against EPA's and WHO's reference points
Against outdoor air (about 0.4 pCi/L)
2.5 times the outdoor average (calculated)Against WHO's recommended reference level (100 Bq/m3, 2.7 pCi/L)
Below itEPA's band
Below EPA's 2 to 4 pCi/L consider-fixing range
What to do
What to do about a radon level of 1 pCi/L
EPA recommends fixing a home when the radon level is 4 pCi/L or higher. EPA recommends considering a fix when the level is between 2 and 4 pCi/L. For a reading of 1 pCi/L, the steps come to this:
Steps for a reading of 1 pCi/L
Check where the test was
A test belongs in the lowest lived-in level. If the test was upstairs, a basement you use may read higher.Keep the result
Save the report; a buyer may ask for it, and it is the baseline for later tests.Test again sometime
Even below 4 pCi/L, you may want to test again in the future.Retest after changes
After a renovation, or if you start using a lower floor, test again on that level.
The full sequence of tests, from a first result to the decision to fix, is drawn on radon testing.
Health risk
The lung cancer risk at 1 pCi/L
EPA's risk chart has no row for 1 pCi/L, so the table shows the rows either side of it. The chart estimates how many people out of 1,000 could get lung cancer if exposed to a level over a lifetime, for people who smoked and people who never smoked.
1 pCi/L sits between the 0.4 and 1.3 pCi/L rows, about two thirds of the way from the lower row (our calculation). At 1.3 pCi/L the chart gives about 20 in 1,000 people who smoked, and about 2 in 1,000 who never smoked; at 0.4 pCi/L, about 3 in 1,000 people who smoked, and no figure for people who never smoked.
| Radon level | People who smoked | People who never smoked | What to do |
|---|---|---|---|
| 1.3 pCi/L (50 Bq/m3) | About 20 in 1,000 | About 2 in 1,000 | Average indoor radon level |
| 0.4 pCi/L (15 Bq/m3) | About 3 in 1,000 | No figure given | Average outdoor radon level |
These are population estimates from EPA's 2003 assessment of radon risk in homes, not a forecast for any one person. Your own chances depend mostly on how much radon is in your home, how much time you spend there, and whether you smoke or have ever smoked; a former smoker's risk may sit between the two columns. Lung cancer risk is estimated to rise by about 16% per 100 Bq/m3 of long-term average radon.
EPA's whole chart, from outdoor air to 20 pCi/L, is drawn on radon levels.
How sure
How certain is a reading of 1 pCi/L?
One test is a sample of a level that moves. Radon levels tend to vary from day to day and season to season, so a is less likely than a to show the year-round average, and levels can change from hour to hour. A single short-term result of 1 pCi/L is a reading for those days.
Where the test sat matters as much. A test belongs in the lowest lived-in level, and levels are usually higher in basements and rooms in contact with the ground. Testing is the only way to know the radon level in a specific building. Placement and are on radon testing.
Lower still?
Can 1 pCi/L be lowered further?
- About 1.3 pCi/L
- EPA's estimate of the average indoor radon level in U.S. homes.
- Below 2 pCi/L
- Reducing radon levels below 2 pCi/L is difficult.
- About 0.4 pCi/L
- The outdoor average: Congress's long-term goal for indoor air.
Sometimes, but EPA does not ask for it. Reducing radon levels below 2 pCi/L is difficult, and Congress's long-term goal, indoor air no higher than outdoor air at about 0.4 pCi/L, is not yet technologically achievable in every home. At 1 pCi/L the practical steps are to keep the result, retest after changes to the house, and test again sometime in the future.
Situations
Where people meet a reading of 1 pCi/L
1 pCi/L in three common situations
1 pCi/L after a mitigation system
As a post-mitigation result, 2.0 pCi/L or below is considered low, so 1 pCi/L says the system is doing its job. Retest at least every two years to be sure it stays low.1 pCi/L upstairs, with a basement you rarely use
A test belongs in the lowest lived-in level, and levels are usually higher in basements. If you start using the basement, retest on that level.1 pCi/L in a home you are selling
Keep the report. A buyer may ask for a new test if the last one is not recent, within two years, or if they plan to live in a lower area of the home than the one tested.
Retest
When to retest after 1 pCi/L
At 1 pCi/L there is no follow-up test to schedule: below 4 pCi/L the guidance is that you may want to test again sometime in the future. Three things bring that forward: starting to use a lower floor such as a basement, a major renovation, and a sale where the last test is more than about two years old. For a home without a system, Minnesota's health department suggests a retest every 5 years.
| When | What to do |
|---|---|
| Sometime in the future | You may want to test again even below 4 pCi/L |
| After a renovation | Major renovations can change the radon level in any home |
| Before using a lower floor | Retest on that level |
| Without a mitigation system | Every 5 years, the Minnesota health department's advice |
| When selling | A buyer may ask for a new test if yours is more than about two years old |
The general answer is on how often should I test for radon.
Questions
Radon level of 1 pCi/L: questions
Is 1 pCi/L of radon safe?
No level is called safe; any radon exposure carries some risk. 1 pCi/L is below the 4 pCi/L action level and below the 2 to 4 range.
Do I need radon mitigation at 1 pCi/L?
EPA does not recommend a fix below 2 pCi/L. Test again in the future and after changes to the house.
What is 1 pCi/L in Bq/m3?
It is about 35 Bq/m3, at about 37 Bq/m3 per pCi/L (our calculation).
Should I buy a house with a radon level of 1 pCi/L?
EPA's guidance for a home under 4 pCi/L is the same whoever owns it: consider a fix from 2 pCi/L. Check that the test was in the lowest level you will use; a buyer may live in a lower area than the seller tested.
Is 1 pCi/L in a basement different from upstairs?
Usually the basement reads higher. Levels are usually highest in basements and rooms in contact with the ground, though considerable levels can occur above the ground floor too. A test belongs in the lowest lived-in level.
How long should I wait to retest after 1 pCi/L?
There is no fixed interval below 4 pCi/L; you may want to test again sometime in the future, and after renovations or a move to a lower floor.
Is 1 pCi/L higher than outdoor air?
Yes. Outdoor air averages about 0.4 pCi/L, so 1 pCi/L is 2.5 times that (our calculation). Congress's long-term goal is indoor air no higher than outdoor air, a goal not yet technologically achievable in all cases.