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Radon Levels

Radon level of 8 pCi/L: what to do

By Radon411 Editorial Team

Updated October 1, 2026

Methodology

Try it

Move a reading around 8 pCi/L

The reading starts at 8 pCi/L. Slide it to see where EPA's guidance changes and how far this number is from each line.

Read a result for 8 pCi/L

Starts at 8.0 pCi/L, this page's reading

8.0pCi/L

EPA’s own thresholds, as its guidance states them.

EPA’s reading of 8.0 pCi/L

At or above 4 pCi/L

  1. Under 20 to 1.9 pCi/L
  2. 2 to 4consider a fix
  3. 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 4.0 pCi/L above EPA's action level, 2.0 times it.

Short answer

A radon level of 8 pCi/L is twice the 4 pCi/L action level, and the advice is to fix the home once the result is confirmed. A first short-term result more than twice the action level calls for a second short-term test immediately; 8 pCi/L is right at that line, and the higher the first result, the more a quick short-term follow-up makes sense.

Next step: pick the right test for your home. Which test to use

Key takeaways

  • 8 pCi/L is 2 times EPA's 4 pCi/L action level.
  • At or above EPA's action level: fix once confirmed.
  • EPA estimates the average U.S. home at about 1.3 pCi/L; 8 pCi/L is 6.15 times that.
  • Confirm a short-term result with a second test; a long-term test shows the year-round average best.

Where it sits

Is a radon level of 8 pCi/L high?

EPA's risk chart has a row for 8 : about 120 lung cancers per 1,000 people who smoked and about 15 per 1,000 who never smoked, over a lifetime, a smokers' figure about 30 times the risk of dying in a fall. 8 pCi/L is about 300 , which is also the most WHO says any country's reference level should be.

300 Bq/m3
8 pCi/L in becquerels per cubic meter, the published figure.
2 times
EPA's 4 pCi/L action level (calculated).
6.15 times
The U.S. indoor average of about 1.3 pCi/L (calculated).
Read moreTwo paragraphs and a table, 1 min

Because 8 pCi/L is exactly twice the , it is the reading at which EPA's protocol switches from either kind of follow-up test to a second immediately. Bringing it to 2 pCi/L takes a 75% reduction, by our calculation, inside the up to 99 percent EPA cites; a confirmed 8 pCi/L is also 20 times the outdoor average.

Where 8 pCi/L sits against EPA's and WHO's reference points

  • Against outdoor air (about 0.4 pCi/L)

    20 times the outdoor average (calculated)
  • Against WHO's recommended reference level (100 Bq/m3, 2.7 pCi/L)

    Above it
  • EPA's band

    At or above EPA's action level: fix once confirmed

Other readings explained: 1 pCi/L, 2 pCi/L, 3 pCi/L, 4 pCi/L, 5 pCi/L, 6 pCi/L, 7 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 8 pCi/L

EPA recommends fixing a home when the radon level is 4 pCi/L or higher. For a reading of 8 pCi/L, the steps come to this:

Steps for a reading of 8 pCi/L

  1. Confirm it

    If 8 pCi/L was a first short-term result, take a follow-up test: a long-term test for the year-round average, or a second short-term test if you need results quickly.
  2. Decide on the confirmed number

    EPA recommends fixing a home when the radon level is 4 pCi/L or higher. The decision rests on one long-term test or the average of two short-term tests: two results averaging 8 pCi/L call for the fix.
  3. Hire a qualified contractor

    Get more than one estimate and a written contract; see radon mitigation.
  4. 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 8 pCi/L

EPA's risk chart has a row for 8 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.

EPA's risk chart row for 8 pCi/L
Radon levelPeople who smokedPeople who never smokedWhat to do
8 pCi/L (300 Bq/m3)About 120 in 1,000About 15 in 1,000Fix your home
Read moreTwo paragraphs, 1 min

At 8 pCi/L, the chart's lifetime estimate is about 120 in 1,000 people who smoked (30 times the risk of dying in a fall), and about 15 in 1,000 who never smoked (4 times the risk of dying in a fall). 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 300 Bq/m3, a long-term average of 8 pCi/L, that comes to about 48% 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 8 pCi/L?

A first short-term result of 8 pCi/L is enough to act on only once a second test agrees: radon varies from day to day and season to season, and a is likelier to show the year-round average. At 8 pCi/L, a year-round average a third lower would be 5.33 pCi/L, still at or above the action level.

Read moreA note, 1 min

With a system

How much a radon system would lower 8 pCi/L

From 8 pCi/L, an active system at the low end of its typical range would leave about 4 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 0.08 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.

What the typical reductions would leave from 8 pCi/L (calculated)
TechniqueTypical reductionFrom 8 pCi/L, about
Active suction: sub-slab, sump hole, drain tile, or a crawl-space membrane50 to 99 percent4 to 0.08 pCi/L
Passive sub-slab suction (no fan)30 to 70 percent5.6 to 2.4 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 8 pCi/L

8 pCi/L in three common situations

  • 8 pCi/L on a long-term test

    A long-term result is the confirmed number. EPA recommends fixing when one long-term test shows 4 pCi/L or more, so there is no further test to take before getting estimates.
  • 8 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.
  • Designing a system for 8 pCi/L

    How many suction pipes a system needs, and where, depends on how easily air moves under the slab and on the strength of the radon source. The contractor may run diagnostic tests first to design it.

Retest

When to retest after 8 pCi/L

8 pCi/L is exactly twice the action level. The trigger for an immediate second short-term test is a first result more than twice 4 pCi/L, so 8 sits right at that line: either follow-up fits, and at a result this high a short-term one is the quicker route to a decision.

When to test again after a reading of 8 pCi/L
WhenWhat to do
To confirm the first resultWith a long-term test, or a second short-term test if you need results quickly
After a system is installedNo sooner than 24 hours and within 30 days, with a two- to seven-day test
With a system in placeAt least every two years
After a remodelIn 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 8 pCi/L: questions

Is 8 pCi/L of radon safe?

No. 8 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 8 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; 8 pCi/L is 2 times that line.

What is 8 pCi/L in Bq/m3?

It is 300 Bq/m3, the figure EPA prints for it.

Should I buy a house with a radon level of 8 pCi/L?

A high level is fixable: from 8 pCi/L, an active system's typical reduction would leave 4 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 8 pCi/L in a basement different from upstairs?

Usually the basement reads higher. If 8 pCi/L came from a room upstairs, a basement half again as high would read 12 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 8 pCi/L?

Follow up soon, with a long-term test if you have time or a second short-term test if you need results quickly: 8 pCi/L is 4 pCi/L over the line.

Is 8 pCi/L above the WHO limit?

Just under it. WHO says national reference levels should not exceed 8.1 pCi/L (300 Bq/m3), and EPA prints 8 pCi/L as 300 Bq/m3.