Radon Level Risk Calculator
Assess your radon exposure risk based on measured radon levels.
Understand EPA action levels and when to mitigate radon in your home.
Radon is a naturally occurring radioactive gas produced by the decay of uranium in soil and rock. It is colorless, odorless, and tasteless — you cannot detect it without a test. Radon is the #2 cause of lung cancer in the United States, responsible for approximately 21,000 deaths per year.
How radon enters homes:
Radon seeps up from the ground through cracks in foundations, floor drains, and construction joints. It accumulates in enclosed spaces — especially basements and ground-floor areas with poor ventilation. Upper floors typically have lower radon levels than ground floors and basements.
Radon measurement units:
- pCi/L (picocuries per liter) — used in the United States
- Bq/m³ (becquerels per cubic meter) — used in Europe and internationally
- Conversion: 1 pCi/L = 37 Bq/m³
EPA radon action levels:
| Radon Level | EPA Guidance |
|---|---|
| Under 2 pCi/L | Average indoor radon (2.7 pCi/L is US average) — no action required |
| 2–4 pCi/L | Below action level, but mitigation should be considered |
| 4 pCi/L+ | EPA action level — fix your home |
| 8–10 pCi/L | High — significant health risk, prioritize mitigation |
| Above 20 pCi/L | Very high — take immediate action |
Lifetime cancer risk estimates (smokers vs non-smokers):
Radon and smoking are a particularly dangerous combination — the risks multiply, not just add.
| Radon Level | Lifetime Risk (never-smoker) | Lifetime Risk (smoker) |
|---|---|---|
| 2 pCi/L | 2.5 in 1,000 | 32 in 1,000 |
| 4 pCi/L | 5 in 1,000 | 62 in 1,000 |
| 8 pCi/L | 10 in 1,000 | 120 in 1,000 |
| 20 pCi/L | 36 in 1,000 | 260 in 1,000 |
Radon mitigation:
The most common solution is sub-slab depressurization (ASD): A pipe is inserted through the floor slab and a fan draws radon out from under the house before it enters the living space. Cost: typically $800–$2,500 for a professional installation. This reduces radon by 50–99% in most homes.
Testing:
- Short-term tests (2–7 days): Use a charcoal canister from a hardware store (~$15–$25)
- Long-term tests (90+ days): More accurate seasonal average
- Professional testing: $100–$300
- Test every 2 years, or after major renovations or changes in HVAC system