Radon in Real Estate Transactions
All Minnesota homes can have dangerous levels of radon gas. Radon is a colorless and odorless gas that
comes from the soil. The gas can accumulate in the home. When inhaled, its radioactive particles can
damage the lungs. Long-term exposure to radon can lead to lung cancer. About 21,000 lung cancer
deaths each year in the United States are caused by radon.
The only way to know how much radon gas has entered the home is to conduct a radon test. MDH
estimates 2 in 5 homes exceed the 4.0 pCi/L (picocuries per liter) action level. Whether a home is old
or new, any home can have high levels of radon.
The purpose of this publication is to educate and inform potential home buyers of the risks of radon
exposure, and how to test for and reduce radon as part of real estate transactions.
Disclosure Requirements
Eective January 1, 2014, the Minnesota Radon
Awareness Act requires specific disclosure and
education be provided to potential home buyers during
residential real estate transactions in Minnesota.
Before signing a purchase agreement to sell or
transfer residential real property, the seller shall
provide this publication and shall disclose in writing to
the buyer:
1.
whether a radon test or tests have occurred on
the property
2.
the most current records and reports
pertaining to radon concentrations within the
dwelling
3.
a description of any radon levels, mitigation,
or remediation
4.
information on the radon mitigation system,
if a system was installed
5.
a radon warning statement
Radon Facts
How dangerous is radon? Radon is the number
one cause of lung cancer in nonsmokers, and
the second leading cause overall. Your risk for
lung cancer increases with higher levels of radon,
prolonged exposure, and whether or not you are a
current smoker or former smoker.
Where is your greatest exposure to radon? For
most Minnesotans, your greatest exposure is at
home where radon can concentrate indoors.
What is the recommended action based on my
results? If the average radon in the home is at or
above 4.0 pCi/L, the home’s radon level should
be reduced. Also, consider mitigating if radon
levels are between 2.0 pCi/L and 3.9 pCi/L. Any
amount of radon, even below the recommended
action level, carries some risk. A home’s radon
levels may change in the future, so test every
2–5 years, or sooner if there is major remodeling
or changes to the foundation, heating, cooling, or
ventilation.
Radon Warning Statement
“The Minnesota Department of Health strongly recommends that ALL home buyers have an indoor radon
test performed prior to purchase or taking occupancy, and recommends having the radon levels mitigated if
elevated radon concentrations are found. Elevated radon concentrations can easily be reduced by a qualified,
certified, or licensed, if applicable, radon mitigator.
Every buyer of any interest in residential real property is notified that the property may present exposure
to dangerous levels of indoor radon gas that may place the occupants at risk of developing radon-induced
lung cancer. Radon, a Class A human carcinogen, is the leading cause of lung cancer in nonsmokers and the
second leading cause overall. The seller of any interest in residential real property is required to provide the
buyer with any information on radon test results of the dwelling.”
Radon Testing
Any test lasting less than three months requires closed-house conditions. Closed-house conditions include
keeping all windows and doors closed, except for normal entry and exit, and temperature set to 65 – 80 F.
For a full list of closed-house conditions please visit mn.gov/radon/notice.
Before testing: Begin closed-house conditions at least 12 hours before the start of the radon test.
During testing: Maintain closed-house conditions during the entire duration of the short-term
test. Operate home heating or cooling systems normally during the test.
Where should the test be conducted? Any radon test conducted for a real estate transaction needs to be
placed in the lowest livable area of the home suitable for occupancy. This is typically in the basement, whether
f inished or unf inished. If other foundations are present, such as a crawl space or slab on grade, also test the
rooms above these foundations.
Place the test kit:
20 inches to 6 feet above the f loor
3 feet from exterior doors and windows
1 foot from exterior walls
away from heat sources and drafts caused by
vents and fans
not in enclosed areas or areas of high heat/humidity
How are radon tests conducted in real estate transactions?
There are special protocols for radon testing in real estate transactions. Because these tests are time-sensitive
there are two testing options. For both tests, test for a minimum of 2 days.
Continuous Radon Monitor (CRM)
MDH recommends CRMs in real estate testing.
CRMs are calibrated, provide more data, and may
detect tampering. The average of the results are
used to make a decision to mitigate.
Simultaneous Short-Term Testing
Two short-term test kits are placed side by side,
4” – 8” apart. The results of the two tests are
averaged and used to make a decision to mitigate.
Radon Mitigation
When elevated levels of radon are found, they can be easily reduced by a licensed professional.
Radon mitigation is the process or system used to reduce radon concentrations in the breathing zones of
occupied buildings. The goal of a radon mitigation system is to reduce the indoor radon levels to below the
action level. This is done by drawing soil gas from under the house and venting it above the roof. A quality
mitigation system is often able to reduce the annual average radon level to below 2.0 pCi/L. The cost of a
radon mitigation system averages $1,500 to $3,000.
After a radon mitigation system is installed perform an independent short-term test to ensure the reduction
system is eective. Operate the radon system during the entire test. This short-term test will confirm low
levels in the home. Be sure to retest the house every two years to confirm continued radon reduction.
All radon testing and mitigation should be conducted by licensed radon professionals. Radon service
providers, such as home inspectors, must be licensed. A list of these licensed radon professionals can be
found at MDH’s radon web site. MDH conducts free inspections, upon request, of recently installed radon
mitigation systems, to check that they meet requirements.
More Radon Information
www.mn.gov/radon
Last Updated 4/2023
MDH Indoor Air Unit
PO Box 64975
St Paul, MN 55164-0975
Contact Information
651-201-4601
800-798-9050
