Radon Levels
Radon level of 10 pCi/L: is it dangerous?
Try it
Move a reading around 10 pCi/L
The reading starts at 10 pCi/L. Slide it to see where EPA's guidance changes and how far this number is from each line.
Read a result for 10 pCi/L
Starts at 10.0 pCi/L, this page's reading
EPA’s own thresholds, as its guidance states them.
EPA’s reading of 10.0 pCi/L
At or above 4 pCi/L
- Under 20 to 1.9 pCi/L
- 2 to 4consider a fix
- 4 and aboveEPA says fix it
This result is at or above 4 pCi/L. EPA recommends fixing a home when the radon level is 4 pCi/L or higher. That is 6.0 pCi/L above EPA's action level, 2.5 times it.
Short answer
A radon level of 10 pCi/L is high: it is 2.5 times the action level, and EPA recommends fixing the home once a second test confirms it. Because it is more than twice the action level, a first short-term result this high calls for a second short-term test immediately.
Next step: pick the right test for your home. Which test to use
Key takeaways
- 10 pCi/L is 2.5 times EPA's 4 pCi/L action level.
- More than twice the action level: confirm right away, then fix.
- EPA estimates the average U.S. home at about 1.3 pCi/L; 10 pCi/L is 7.69 times that.
- Confirm a first short-term result this high with a second short-term test immediately.
Where it sits
Is a radon level of 10 pCi/L high?
EPA's risk chart has a row for 10
- 370 Bq/m3
- 10 pCi/L in becquerels per cubic meter, the published figure.
- 2.5 times
- EPA's 4 pCi/L action level (calculated).
- 7.69 times
- The U.S. indoor average of about 1.3 pCi/L (calculated).
Read moreThree paragraphs and a table, 1 min
The fix is the same as at lower levels: the steps are the same for every confirmed result from 4 pCi/L up, and most homes can be brought to 2 pCi/L or below.
At about 370
Where 10 pCi/L sits against EPA's and WHO's reference points
Against outdoor air (about 0.4 pCi/L)
25 times the outdoor average (calculated)Against WHO's recommended reference level (100 Bq/m3, 2.7 pCi/L)
Above itEPA's band
More than twice the action level: confirm right away, then fix
Other readings explained: 1 pCi/L, 2 pCi/L, 3 pCi/L, 4 pCi/L, 5 pCi/L, 6 pCi/L, 7 pCi/L, 8 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 10 pCi/L
EPA recommends fixing a home when the radon level is 4 pCi/L or higher. For a reading of 10 pCi/L, the steps come to this:
Steps for a reading of 10 pCi/L
Retest right away
10 pCi/L is 2.5 times the action level, more than twice it, so take a second short-term test immediately rather than wait for a long-term test.Check the first test
Improper testing may give inaccurate results; confirm the device, its placement and closed-house conditions.Fix the home
EPA recommends fixing a home when the radon level is 4 pCi/L or higher. Get estimates from qualified contractors; see radon mitigation.Test after the fix
No sooner than 24 hours and within 30 days after the system starts, then at least every two years.
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 10 pCi/L
EPA's risk chart has a row for 10 pCi/L. It estimates how many people out of 1,000 could get lung cancer if exposed to that level over a lifetime, separately for people who smoked and people who never smoked.
| Radon level | People who smoked | People who never smoked | What to do |
|---|---|---|---|
| 10 pCi/L (370 Bq/m3) | About 150 in 1,000 | About 18 in 1,000 | Fix your home |
Read moreTwo paragraphs, 1 min
At 10 pCi/L, the chart's lifetime estimate is about 150 in 1,000 people who smoked (200 times the risk of dying in a home fire), and about 18 in 1,000 who never smoked (20 times the risk of dying in a home fire). The comparisons in parentheses are the ones EPA prints beside the row.
Lung cancer risk is estimated to rise by about 16% per 100 Bq/m3 of long-term average radon. At 370 Bq/m3, a long-term average of 10 pCi/L, that comes to about 59% 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 10 pCi/L?
At 10 pCi/L the question is not whether the home is high but how high, since a day-to-day or seasonal swing cannot explain a reading this far above the
Read moreA note, 1 min
With a system
How much a radon system would lower 10 pCi/L
From 10 pCi/L, an active system at the low end of its typical range would leave about 5 pCi/L, still at or above the action level, so the test after installation decides whether the system is enough; at the high end, about 0.1 pCi/L. Our arithmetic on the published ranges, not a prediction for your house: radon levels in most homes can be reduced to 2 pCi/L or below.
| Technique | Typical reduction | From 10 pCi/L, about |
|---|---|---|
| Active suction: sub-slab, sump hole, drain tile, or a crawl-space membrane | 50 to 99 percent | 5 to 0.1 pCi/L |
| Passive sub-slab suction (no fan) | 30 to 70 percent | 7 to 3 pCi/L |
Read moreA paragraph, 1 min
Which technique fits depends on the foundation; see radon mitigation systems, and for cost, radon mitigation cost.
Situations
Where people meet a reading of 10 pCi/L
10 pCi/L in three common situations
10 pCi/L on a long-term test
That is a confirmed result: EPA recommends fixing when one long-term test shows 4 pCi/L or more. Get estimates rather than another test.10 pCi/L after a mitigation system
As a post-mitigation result, 4.0 pCi/L or greater means fix the building, and with a system already installed, more work may be needed to lower the radon further.10 pCi/L in a home sale
The buyer and seller should discuss the timing and costs of radon reduction, and the contract can say when mitigation will be done and who will pay.
Retest
When to retest after 10 pCi/L
10 pCi/L is 2.5 times the action level, more than twice it, so take a second
| When | What to do |
|---|---|
| To confirm the first result | Immediately, with a second short-term test |
| After a system is installed | No sooner than 24 hours and within 30 days, with a two- to seven-day test |
| With a system in place | At least every two years |
| After a remodel | In the lowest lived-in area |
Show all 4 rows
Read moreA paragraph, 1 min
The general answer is on how often should I test for radon.
Questions
Radon level of 10 pCi/L: questions
Is 10 pCi/L of radon safe?
No. 10 pCi/L is at or above EPA's 4 pCi/L action level, where EPA recommends fixing the home once the result is confirmed.
Do I need radon mitigation at 10 pCi/L?
Yes, by EPA's guidance, once a long-term test or the average of two short-term tests confirms the level is 4 pCi/L or more; 10 pCi/L is 2.5 times that line.
What is 10 pCi/L in Bq/m3?
It is 370 Bq/m3, the figure EPA prints for it.
Should I buy a house with a radon level of 10 pCi/L?
A high level is fixable: from 10 pCi/L, an active system's typical reduction would leave 5 pCi/L or less. Buyers and sellers should discuss the timing and costs of radon reduction, and the contract can say when mitigation happens and who pays. See should I buy a house with radon.
Is 10 pCi/L in a basement different from upstairs?
Usually the basement reads higher. If 10 pCi/L came from a room upstairs, a basement half again as high would read 15 pCi/L, at or above the action level; a test belongs in the lowest lived-in level.
How long should I wait to retest after 10 pCi/L?
Do not wait: 10 pCi/L is more than twice the action level, and a first short-term result that high calls for a second short-term test immediately.
How far would a system bring 10 pCi/L down?
Active soil suction typically cuts radon by 50 to 99 percent: from 10 pCi/L, to 5 pCi/L or lower at the low end (our calculation). Reaching 2 pCi/L takes an 80 percent cut, inside that range. The post-mitigation test shows the real result.