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What Is Radon? A Plain-English Guide for Northeast Ohio Homeowners

No jargon. No scare tactics. Just what radon is, why it matters, and what you should actually do about it.
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Radon by the numbers
Atomic number: 86
State at room temperature: gas
Half-life: 3.8 days
Source: decay of uranium-238 in soil and rock
Measured in: picocuries per liter (pCi/L) in the U.S
The Science

What Radon Actually Is

Radon is a naturally occurring radioactive gas. It forms when uranium, which exists in trace amounts in nearly all soil, breaks down over millennia. Because radon is a gas and uranium is in the ground, radon rises through soil and rock toward the surface. Most of it dissipates harmlessly into the atmosphere. Some of it ends up under, and inside, the homes built on top of it.
Three plain facts
  • Radon has no color. You cannot see it.
  • Radon has no smell. You cannot smell it.
  • Radon has no taste. You cannot taste it.
The only way to know if it's in your home is to measure it with calibrated equipment. There is no other way. Air fresheners don't help, opening a window doesn't fix the problem, and dehumidifiers do nothing to radon.
The Health Risks

Why It Matters: The Lung Cancer Connection

According to the EPA and the U.S. Surgeon General, radon is the second leading cause of lung cancer in the United States after smoking, and the leading cause of lung cancer in non-smokers. Roughly 21,000 lung cancer deaths each year in the U.S. are attributed to radon exposure.

The risk isn't from a single exposure. It comes from breathing radon at elevated levels for years or decades. As radon decays, it produces tiny radioactive particles. When you breathe them in, those particles lodge in the tissue of your lungs, where they continue to release small amounts of radiation. Over years, that radiation damages lung cells in ways that can lead to cancer.

Smokers have a significantly higher risk than non-smokers at the same radon level. The two exposures compound each other.
The Numbers
21,000
estimated annual lung cancer deaths attributed to radon in the U.S. (EPA, A Citizen's Guide to Radon)
#1
cause of lung cancer among people who have never smoked (EPA, Surgeon General)
#2
cause of lung cancer overall, after smoking (EPA)
EPA Zone 1
Northeast Ohio. The highest-risk zone in the EPA's three-tier map.
How Radon Enters a Home

How Radon Gets Inside

Radon rises from the soil under your foundation. Any gap, crack, or opening between that soil and the air inside your house is a potential entry point. In a typical home, these include:
  • Foundation cracks (especially in basement floors and walls)
  • Construction joints (where the floor slab meets the foundation wall)
  • Gaps around plumbing, drains, and utility penetrations
  • Sump pump pits and floor drains
  • Crawl spaces with bare soil floors
  • Slab penetrations and expansion joints
Once radon enters, the home's natural air pressure (which is usually slightly lower than the soil outside) pulls more in. The gas then accumulates in the lower levels first. Basements typically have higher readings than first floors, which have higher readings than second floors.
The EPA Action Level

What 4.0 pCi/L Actually Means

Radon levels are measured in picocuries per liter, written as pCi/L. The EPA's recommended action level is 4.0 pCi/L. At or above this number, the EPA recommends installing a mitigation system.
This is not a "safe vs. unsafe" line. The EPA is explicit: there is no fully safe level of radon. 4.0 pCi/L is simply the threshold at which the risk justifies the cost of mitigation for most homes. Many health authorities, including the World Health Organization, recommend considering mitigation between 2.0 and 4.0 pCi/L as well.
Routing options table
Reading
Under 2.0 pCi/L
2.0 to 3.9 pCi/L
4.0 to 9.9 pCi/L
Cost (typical)
What it means
Below most action thresholds.
Below the EPA action level but not negligible.
At or above the EPA action level.
Significantly elevated.
What to do
Retest every 2 to 5 years, or after any major renovation.
Consider mitigation. Re-test annually.
Mitigation recommended. Long-term retest or mitigate.
Mitigation recommended without delay.
FAQS

Common Questions, Plainly Answered.

Radon levels can vary dramatically between houses on the same street, sometimes by a factor of 10 or more. Soil composition, foundation type, ventilation, and construction details all matter. Your neighbor's test tells you nothing about your home.

New construction does not prevent radon. In fact, tighter modern homes can sometimes trap radon at higher concentrations than older, drafty homes. Many new homes still test above the action level.

Finishing a basement (drywall, flooring, ceiling) doesn't seal radon out. It often just hides the entry points behind walls. Some finished basements test higher than unfinished ones because there's less natural air exchange.

Opening windows briefly will dilute radon levels temporarily, but radon enters the home continuously from the soil. As soon as the windows close, levels return to normal within hours. Year-round mitigation is the only durable fix.

Consumer-grade detectors vary widely in accuracy. They are useful for ongoing awareness once you've done a calibrated baseline test. They are not a substitute for professional measurement, especially for real estate transactions or initial assessment.

Why Northeast Ohio Specifically

Why Radon Matters
 More Here Than in Most Places

Northeast Ohio sits in EPA Zone 1, the highest of three radon zones the EPA uses to map national risk. Zone 1 counties are predicted to have an average indoor radon level above 4.0 pCi/L, the action threshold.

The reason is geological. The glacial till and uranium-bearing shale common across Cuyahoga, Summit, Lake, Lorain, Stark, Ashtabula, and Erie counties produce more radon than the soil in much of the rest of the country. This is not anyone's fault and not a flaw in your home. It's just the ground we live on.

The practical result: if you live in one of these seven counties and have not tested your home in the last few years, you have a meaningfully higher probability of an elevated reading than the average American homeowner.
What to Do Next

Your Three Next Steps

Test your home. A professional 48-hour test gives you a calibrated, defensible reading. Most homes test in the under-2 range and need no further action. Some don't. You can't know until you measure.
01
Test your home. A professional 48-hour test gives you a calibrated, defensible reading. Most homes test in the under-2 range and need no further action. Some don't. You can't know until you measure.
02
If your reading is at or above 4.0 pCi/L, schedule a mitigation quote. Most homes drop below 1.0 pCi/L after a same-day installation
03
Retest periodically. Once every 2 to 5 years for mitigated homes, every 2 to 5 years for low-reading homes, and any time you make a major change like a renovation, a foundation repair, or an HVAC swap.

Have Questions or Ready to Test?

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Sources & Citations

1. U.S. Environmental Protection Agency, A Citizen's Guide to Radon: epa.gov/radon/citizens-guide-radon
2. U.S. Surgeon General, Radon Health Advisory (2005)
3. World Health Organization, WHO Handbook on Indoor Radon (2009)
4. PA Radon Zones Map: epa.gov/radon/find-information-about-local-radon-zones-and-state-contact-information
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