Radon mitigation basics
How radon reduction systems work, who can install them in NH, and what to check afterward.
How a typical system works
The most common approach draws radon from under the home before it gets inside: a pipe through the basement or crawl space floor, routed outside, with a fan that exhausts the air. NH DHHS says these systems are very good at keeping levels below 4 pCi/L year round.
What doesn't work on its own
Sealing cracks alone does little, though it can make a system work better. NH DHHS advises against spending on “radon barrier” or “radon sealant” paints instead of a system.
Who installs it
In New Hampshire, contractors who install air radon systems must be nationally certified. Find certified professionals through NRPP or NRSB. The state does not license or endorse individual mitigators, and RadonRundown doesn't recommend specific contractors.
Cost
NH DHHS's 2016 fact sheet put air mitigation systems at $1,000 to $3,000 and well-water aeration at $4,000 to $6,000. Those are 2016 figures; get current quotes.
After installation
- Retest to confirm the system works (see when to retest).
- Fans are usually good for 10 to 15 years before needing replacement, per NH DHHS.
In New Hampshire? Order a free state test kit or see radon by NH county.
More guides
- How to read a radon test result (pCi/L)
- Short-term vs long-term radon tests
- Radon testing when buying or selling a home in NH
- Radon in well water in New Hampshire
- When to retest for radon
Sources
- NH DHHS, Fixing Radon: Mitigation
- NH DHHS Environmental Public Health Tracking, “Spotlight: Radon Risk,” Jan 2016 (NH DES test data, 1988–2011)
- EPA, A Citizen's Guide to Radon
Sources checked October 31, 2026. Spot an error? Send a correction.