Radon is measured in pCi/L, and the EPA says to fix a home at 4.0 or above. There is no truly safe level, but most homes sit under 2 and 4-plus is where you act. New Hampshire granite pushes a lot of homes over that line, so a test is the only way to know where you stand.
Radon is an invisible, odorless radioactive gas that can accumulate in homes, particularly in New England. In towns like Exeter, Kingston, Hampton, Dover, Stratham, Portsmouth, and Brentwood, older homes with basements or crawl spaces are especially at risk.
The danger of radon comes from its long-term exposure. Even low levels over time can increase your risk of lung cancer. Knowing your home’s radon level is critical for safety.
How Radon Levels Are Measured
Radon is measured in picocuries per liter (pCi/L). Professional testing kits or certified radon testers can determine the concentration in your basement or living areas.
- Short-term tests: Typically 2–7 days, useful for a quick snapshot.
- Long-term tests: 90 days to 1 year, providing a more accurate average over seasons.
Seasonal changes, soil moisture, and ventilation can all affect readings, which is why repeated or long-term testing is often recommended in New England homes.
What Levels Are Considered Safe or Dangerous
- Below 2.0 pCi/L: Generally considered low risk. Continue periodic testing.
- 2.0–4.0 pCi/L: Moderate risk, mitigation may be recommended depending on home construction and occupancy.
- Above 4.0 pCi/L: Dangerous, immediate professional mitigation is recommended.
The EPA benchmark of 4.0 pCi/L is the accepted action level. Levels above this indicate that radon exposure is significant enough to pose serious health risks over time.
Why Even Slightly Elevated Levels Matter
Radon exposure is cumulative, the longer you’re exposed, the higher your risk. Even levels slightly above 4.0 pCi/L should not be ignored:
- Older homes in Exeter, Kingston, Hampton, Dover, Stratham, Portsmouth, Plaistow, Seabrook, Brentwood, and Haverhill (MA) often have cracks in foundations or slab floors that allow radon to enter.
- Seasonal frost heaves and soil shifts can cause radon levels to fluctuate, sometimes spiking above safe limits.
- Professional mitigation ensures that even small leaks are addressed, preventing future health risks.
Professional Radon Mitigation Solutions
If your levels exceed 4.0 pCi/L, professional intervention is the safest approach:
- Sub-slab suction systems: Draw radon from beneath the foundation and vent it safely outside.
- Radon-compatible drainage and waterproofing: Ensure that water management systems do not interfere with radon airflow.
- Crawl space ventilation: Reduces radon accumulation under homes without basements.
- Continuous monitoring: Professionals can install systems that allow ongoing checks to ensure levels remain safe.
DIY fixes cannot reliably reduce radon levels and can sometimes make the problem worse. Only trained professionals can measure, install, and maintain systems to protect your family.
The bottom line
Radon is invisible, but the risk is real. Anything above 4.0 pCi/L should be taken seriously.
At 603 Basement Solutions in East Kingston, NH, we provide professional radon testing and mitigation for homes across Exeter, Kingston, Hampton, Dover, Stratham, Portsmouth, Plaistow, Seabrook, Brentwood, and Haverhill (MA). Protect your home and family by scheduling a professional evaluation today, ensuring your radon levels are safe and your basement remains dry.
📞 Contact us now for professional radon testing and mitigation solutions.
Frequently asked questions
What radon level is dangerous?
The EPA action level is 4.0 pCi/L, that is where they recommend a mitigation system. There is no level that is completely risk-free, so lower is always better, but 4 and up is where you should act.
Is 2 pCi/L safe?
2 is on the lower end and below the EPA action level, so most people leave it. If it is a bedroom or a space you spend a lot of time in, some folks choose to mitigate anyway. We will give you a straight read, not a scare.
How accurate is a radon test?
A proper test is accurate enough to act on. Radon swings with the seasons and weather, so a longer test or a retest gives you a truer picture than a single short one.
Related from 603
More on radon levels: Is a 2 pCi/L bedroom level safe? · How to test radon · our radon mitigation page.
