Short answer
pCi/L stands for picocuries per liter of air. It is the unit a radon test result is reported in across the United States.
What pCi/L means
The prefix pico means one trillionth, so a picocurie is one trillionth of a curie, a unit of radioactivity. A result in pCi/L counts the radioactivity from radon in each liter of the air the test sampled.
Most of the world reports radon in
pCi/L turned into Bq/m³, level by level
Each row multiplies a level on EPA's risk chart by 37. EPA prints a rounded figure beside the same level, shown in the last column.
| Level, pCi/L | Times 37, Bq/m³ | As EPA prints it, Bq/m³ |
|---|---|---|
| 0.4 | 14.8 | 15 |
| 1.3 | 48.1 | 50 |
| 2 | 74 | 75 |
| 4 | 148 | 150 |
| 8 | 296 | 300 |
| 10 | 370 | 370 |
| 20 | 740 | 740 |
What it means for your home
On a home test, hold the number against 4 pCi/L. EPA says to fix a home at 4 pCi/L or more and to consider fixing between 2 and 4 pCi/L. For scale, EPA puts the average indoor level at about 1.3 pCi/L and normal outdoor air at about 0.4 pCi/L.
No reading is a clean bill of health. EPA believes any radon exposure carries some risk, and CDC says to always aim for the lowest level.
Where to go next
- Radon level interpreter. Enter your test result and read what EPA says to do at that level.
- What 2, 4, 5 and 10 pCi/L mean. The common results, one by one, with EPA's step for each.