You just moved into your Morris County home and want to be sure it’s healthy and safe. Radon is invisible, odorless, and can change over time, so a one-and-done test at closing may not tell the whole story. In this guide, you’ll learn when to retest, which tests to use, who can perform them in New Jersey, what your results mean, and what it may cost. Let’s dive in.
Radon risk in Morris County
Radon is a natural gas that can build up indoors and increase lung cancer risk. The EPA recommends fixing homes with average results at or above 4.0 pCi/L, and notes there is no known safe level of radon. You should also consider mitigation between 2.0–4.0 pCi/L. See the EPA’s explanation of the action level and risk for context on this page.
Morris County sits in a higher‑potential area on federal and state radon maps, but levels vary house to house. That is why testing and retesting are important for every home. You can view the EPA’s Map of Radon Zones for regional context.
When to retest after you buy
If the last professional radon test is not recent, you should run a new one. The EPA notes buyers can ask for a new test if the prior test is not recent, such as not within 2 years. See the EPA’s guidance on retesting frequency here.
Retest sooner if you plan to use lower levels more often, if you completed renovations, altered HVAC systems, or repaired the foundation. These changes can affect how radon enters and moves in a home. When in doubt, schedule a new test to verify current conditions.
After a mitigation system
If your home has a new mitigation system, verify it is working. Industry standards call for a short‑term post‑mitigation test no sooner than 24 hours after system activation and typically within 30 days. You can review the timing discussed in the ANSI/AARST protocols here.
For a fuller picture of annual exposure, follow up with a long‑term test of 90+ days during a typical season, such as heating season. The CDC explains long‑term testing and how to interpret results on this page.
Which test to use
Short‑term tests run for about 2 to 7 days and give quick answers for real estate or post‑mitigation checks. Follow closed‑house conditions during the test. Keep windows and exterior doors closed except for normal entry and exit, and place the device where you spend time on the lowest lived‑in level.
Long‑term tests run for 90 days or more and are best for estimating your annual average radon level. If your short‑term result is borderline or you want the most accurate view of exposure over time, choose a long‑term test. Professionals may also use continuous radon monitors that record hourly data, which can help diagnose patterns.
How to read results
- If your average is 4.0 pCi/L or higher, plan to mitigate. The EPA recommends fixing at this level. Learn more about the action level here.
- If your result is between 2.0–4.0 pCi/L, consider mitigation, since risk increases with level and lower is better.
- If a short‑term result is 4.0 pCi/L or higher, confirm with a second short‑term test or a long‑term test. The CDC outlines these next steps on its testing page.
Who can test or fix in New Jersey
For any paid radon testing or mitigation in New Jersey, the provider must be certified by the NJDEP Radon Program. Real estate transaction tests should be performed by NJDEP‑certified measurement businesses, and mitigation must be done by NJDEP‑certified mitigators. You can learn about certification and find resources through the NJDEP Radon Program.
Typical costs and warranties
DIY short‑term kits are generally inexpensive at retail, while professional real estate tests cost more due to equipment and reporting. For mitigation, NJDEP indicates a typical New Jersey cost around $1,200, with a range of about $500–$2,500, depending on the home. You can review state guidance on costs and radon in homes here.
Many mitigation systems include a fan with a manufacturer warranty that often runs several years. Ask for written documentation and warranty terms with your installation.
Keep your documents for future disclosure
New Jersey law requires home sellers to provide buyers, at contract time, with copies of any radon test results and evidence of any mitigation or treatment performed on the property. Plan to keep your reports and mitigation records organized for your future sale. You can read the statute summarized on this page.
Ongoing retesting schedule
- With an active mitigation system: retest at least every 2 years, and after any changes to the system or major structural/HVAC work. The EPA explains how to confirm a system is working here.
- Without a mitigation system: consider retesting every 3–5 years, or sooner if you make changes to the home or your living patterns.
Quick retesting checklist
- Review the seller’s radon documents, including any test results and mitigation evidence provided at contract time. Confirm dates and levels. See the NJ disclosure rule here.
- If there is no recent professional test or you will use a lower level more often, schedule a short‑term test now. For transaction or paid testing, choose an NJDEP‑certified company via the NJDEP Radon Program.
- If results are 4.0 pCi/L or higher, hire a certified mitigator and require a post‑mitigation verification test within about 30 days, but not sooner than 24 hours after activation. See timing in the ANSI/AARST protocols here.
- Follow up with a long‑term test during a typical season to confirm annual exposure. The CDC explains long‑term testing here.
- Keep all reports, system specs, and warranties for your records and future disclosure.
Local resources
- NJDEP Radon Program: certification, homeowner guidance, and hotline support. Explore the program and resources here. Hotline: 800‑648‑0394.
- Post‑mitigation test support: NJDEP may provide a verification test in some cases. Learn how to request it here.
- Morris County outreach: Municipalities sometimes highlight Radon Action Month in January and may offer limited test kits. See a county announcement and resources on this page.
Whether you just closed in Morristown, Randolph, or Mount Olive, a clear retesting plan protects your health and your investment. If you want help coordinating certified testing, reading results, or navigating next steps ahead of a future sale, reach out to MaryBeth Tomaro for local guidance.
FAQs
What is a safe radon level for a Morris County home?
- The EPA recommends fixing at or above 4.0 pCi/L and considering mitigation between 2.0–4.0 pCi/L; there is no known safe level.
How soon should I retest after installing a radon system?
- Run a short‑term verification test no sooner than 24 hours after activation and typically within 30 days, then follow with a long‑term test for annual exposure.
Who is allowed to perform radon testing in New Jersey?
- Any paid radon testing or mitigation must be done by NJDEP‑certified businesses; use certified professionals for real estate and post‑mitigation tests.
How often should I retest a mitigated home?
- Retest at least every 2 years, and after any major changes to the home or mitigation system, to confirm ongoing performance.
How much does radon mitigation usually cost in New Jersey?
- NJDEP reports a typical cost around $1,200, with a range of about $500–$2,500 depending on the home and system.