Radon Levels
Radon level of 1 pCi/L: is it safe?
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Move a reading around 1 pCi/L
The reading starts at 1 pCi/L. Slide it to see where EPA's guidance changes and how far this number is from each line.
Read a result for 1 pCi/L
Starts at 1.0 pCi/L, this page's reading
EPA’s own thresholds, as its guidance states them.
EPA’s reading of 1.0 pCi/L
Below 2 pCi/L
- Under 20 to 1.9 pCi/L
- 2 to 4consider a fix
- 4 and aboveEPA says fix it
This result is below 2 pCi/L, the level at which EPA says a fix should be considered. That is 3.0 pCi/L below EPA's action level, 0.3 times it.
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?
EPA's risk chart puts the national indoor average, 1.3
- 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).
Read moreThree paragraphs and a table, 1 min
WHO's recommended reference level is 100
In becquerels, 1 pCi/L is about 37 Bq/m3, a little over a third of WHO's 100 Bq/m3 reference level and about 2.5 times the outdoor average of 0.4 pCi/L, by our calculation. The reading is worth keeping: EPA's advice is to test again after major renovations, because work on the house can change the level.
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
Other readings explained: 2 pCi/L, 3 pCi/L, 4 pCi/L, 5 pCi/L, 6 pCi/L, 7 pCi/L, 8 pCi/L, 10 pCi/L, 12 pCi/L, 20 pCi/L, 30 pCi/L, 100 pCi/L.
What to do
What to do about a radon level of 1 pCi/L
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 1 pCi/L came from a room 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
1 pCi/L is 1 pCi/L under the 2 pCi/L point where EPA suggests considering a fix; 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.
Read moreA paragraph, 1 min
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.
| 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 |
Read moreTwo paragraphs, 1 min
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.
Lung cancer risk is estimated to rise by about 16% per 100 Bq/m3 of long-term average radon. At 35 Bq/m3, a long-term average of 1 pCi/L, that comes to about 6% above the risk with no radon at all (our calculation, a population estimate, not a forecast for one person); a former smoker's risk may sit between the chart's two columns.
How sure
How certain is a reading of 1 pCi/L?
A
Read moreA note, 1 min
Lower still?
Can 1 pCi/L be lowered further?
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.
- 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.
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
| 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 |
Show all 5 rows
Read moreA paragraph, 1 min
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, and 1 pCi/L is 1 pCi/L under it. 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, and 1 pCi/L is under that range. 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. If 1 pCi/L came from a room upstairs, a basement half again as high would read 1.5 pCi/L, still under 2; 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; at 1 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.