ResourcesGlossary: units and levels
Reference level
Short answer
A reference level is the national radon benchmark WHO asks each country to set for homes: 100 Bq/m³ as an annual average where possible, and never above 300 Bq/m³.
What reference level means
EPA gives the same recommendation in U.S. units: 2.7
EPA says the recommendation does not directly affect its 4 pCi/L
WHO's reference level beside EPA's action level
Each row divides a figure in
| Benchmark | Bq/m³ | pCi/L |
|---|---|---|
| WHO's reference level | 100 | 2.70 |
| EPA's action level | 148 | 4.00 |
| WHO's ceiling for a national reference level | 300 | 8.11 |
| EPA's action level less WHO's reference level | 48 | 1.30 |
What it means for your home
For a home in the United States the working numbers stay EPA's: fix at 4 pCi/L, consider fixing between 2 and 4.
A result between 2.70 and 4 pCi/L is above WHO's reference level and inside the range where EPA says to consider fixing.
Where to go next
- Radon level interpreter. Check a result against EPA's two levels.
- Radon limits: EPA's action level and WHO's reference level. Whose limit says what, and what counts as acceptable.