Symptoms of Radon Gas in Your Home: Honest EPA Answer
Searching for “symptoms of radon gas in your home” usually starts from a reasonable assumption: if a gas is in the home and the gas is dangerous, the body should signal something. With radon, that assumption is wrong, and the wrongness matters. Radon does not cause acute symptoms or “radon poisoning” as a clinical event. It is an odorless, colorless, tasteless radioactive gas. Per the U.S. Surgeon General and EPA, radon is the second-leading cause of lung cancer after smoking — responsible for approximately 21,000 deaths per year in the U.S. — but only after long-term exposure (typically 5 to 25+ year latency). There are no immediate symptoms, signs, or “poisoning event.” If you have acute respiratory concerns, see a physician — those symptoms are not caused by radon.
Part of our Radon Levels guide — start there for the full picture →
This guide summarizes EPA, CDC, U.S. Surgeon General, American Lung Association, and CDPHE guidance current as of 2026. It is informational, not medical advice; consult your physician for any health symptoms and a certified radon professional for testing and mitigation decisions. For the broader topic context, see the radon testing pillar guide for Colorado homeowners.
Why “symptoms of radon gas in your home” is the wrong search
The question implies that radon present in a home produces a noticeable bodily response. It does not. Radon is undetectable to all five human senses. There is no smell, no taste, no irritation, no headache, no dizziness, no nausea, and no respiratory symptom that radon causes acutely. Homes with radon levels of 50 pCi/L (more than 12 times the EPA action level) feel identical to homes with 0.4 pCi/L. Senses cannot replace a radon test.
This matters because homeowners who feel “fine” sometimes conclude their home is “fine.” The conclusion is unsupported. The only way to know whether radon is present in a home at concerning levels is to test for it. EPA recommends every home be tested regardless of construction age, geography, or perceived risk.
What radon actually is and how it harms health
Radon is a naturally occurring radioactive gas produced by the decay of uranium in soil and rock. It enters homes through foundation cracks, sump pump pits, slab joints, and crawl spaces. Once inside, it can accumulate to concentrations above ambient outdoor levels (typically 0.4 pCi/L outdoors).
The health risk comes from radon’s decay products (sometimes called radon progeny or radon daughters) — short-lived radioactive isotopes that attach to dust and aerosols in indoor air. When inhaled, these decay products lodge in lung tissue and emit alpha radiation. Alpha radiation damages DNA in lung cells. Over years to decades, that damage can produce mutations that lead to lung cancer. The mechanism is statistical and cumulative — there is no single “exposure event” that causes disease.
The Surgeon General and EPA estimate that radon causes approximately 21,000 lung cancer deaths per year in the U.S., the majority among never-smokers or former smokers. The American Lung Association confirms this estimate. Smoking and radon exposure together multiply risk significantly more than either alone.
What homeowners actually experience with radon
Nothing physically perceptible. Homeowners with radon levels of 20 pCi/L (five times the action level) experience zero acute symptoms attributable to radon. They breathe normally, sleep normally, and have no respiratory irritation from radon itself. The long-term cancer risk is real, but it does not announce itself acutely.
If a homeowner is experiencing acute respiratory symptoms (cough, wheezing, shortness of breath, chest pain, sinus issues, headaches, fatigue), the cause is almost certainly something other than radon: viral or bacterial infection, allergies, indoor air quality issues from mold or VOCs, carbon monoxide (which is a real acute poisoning concern — install a CO detector), HVAC issues, or an unrelated medical condition. See a physician for symptom evaluation.
What radon symptoms look like — when they finally appear
Radon-caused lung cancer presents the same way other lung cancers present: persistent cough that does not resolve, coughing blood, chest pain, shortness of breath, recurring bronchitis or pneumonia, wheezing, hoarseness, and unexplained weight loss. These symptoms typically appear after years to decades of exposure and represent established disease, not acute exposure response.
By the time symptoms appear, the disease is usually well-established. This is exactly why EPA recommends testing — the disease is preventable through mitigation if radon is detected and reduced before decades of exposure accumulate. The companion piece on radon cancer symptoms covers this in depth.
The Colorado Front Range radon picture
The Front Range is geologically a high-radon zone. Uranium and radium occur naturally in the granitic and metamorphic rock underlying much of the region. EPA’s Map of Radon Zones classifies Adams, Arapahoe, Boulder, Broomfield, Denver, Douglas, El Paso, Jefferson, and many other Front Range counties as Zone 1 (highest potential) or Zone 2. CDPHE measurements show that approximately half of Colorado homes test above the 4.0 pCi/L EPA action level.
The geographic reality means Front Range homeowners are statistically more likely to have elevated radon than homeowners in lower-risk regions. It does not mean every home is high — some Zone 1 homes test at 1 pCi/L, others at 30 pCi/L. The only way to know is to test the specific home.
How testing works
Two types of test exist: short-term (2 to 90 days) and long-term (90+ days). Short-term tests give a quick snapshot for real estate transactions and initial screening. Long-term tests average across seasons and give a more accurate annual exposure estimate. Both types are valid; EPA recommends short-term first, with confirmatory testing if the first result is above 4.0 pCi/L.
Test kits are available from hardware stores, CDPHE (which offers discounted kits for Colorado residents), and certified radon measurement professionals. DIY kits cost $15 to $50; professional measurement with a continuous radon monitor (CRM) runs $150 to $300. See the sibling guide on radon test kits for Colorado homeowners.
What to do if the test result is high
EPA action level: 4.0 pCi/L. World Health Organization recommends action at 2.7 pCi/L. Above 4.0 pCi/L, EPA recommends mitigation. Above 8 pCi/L, mitigation is more urgent. Mitigation by a certified radon mitigation contractor typically installs an active soil depressurization (ASD) system — a fan-and-vent system that pulls radon from beneath the foundation and exhausts it above the roofline. Front Range pricing typically runs $1,200 to $2,500 for a residential mitigation.
A successful ASD system typically reduces indoor radon to below 2.0 pCi/L, and usually to below 1.0 pCi/L. Post-mitigation testing confirms the reduction. The sibling piece on radon mitigation system Colorado covers the installation process.
When to see a physician versus when to test the home
If a homeowner has acute symptoms, see a physician. Acute respiratory symptoms are never caused by radon directly. If a homeowner wants to know whether radon exposure is occurring, test the home. Symptoms cannot substitute for testing because radon produces no symptoms acutely.
For long-term lung cancer screening, the National Cancer Institute and U.S. Preventive Services Task Force recommend annual low-dose CT screening for adults aged 50 to 80 with significant smoking history. Radon exposure history is part of the risk discussion with a physician, alongside smoking and occupational exposures.
How long radon exposure takes to cause disease
EPA and CDC characterize radon lung cancer risk as cumulative across years to decades. The risk scales with the product of concentration and time, often expressed in working-level-months (WLM). Higher concentrations and longer exposure raise risk. A homeowner who has lived in a 15 pCi/L home for 20 years has substantially higher accumulated risk than one who lived in a 4 pCi/L home for 5 years. This is why the EPA action level matters and why mitigation reduces future risk dramatically.
What testing protocol works best
EPA recommends short-term testing first (2 to 7 days) as a screening step, then long-term confirmation (90+ days) if the initial result is elevated. Place the test kit in the lowest occupied level of the home — typically the basement if the basement is used for sleeping, working, or extended living, otherwise the lowest occupied floor. Keep windows and exterior doors closed as much as practical during the test (closed-house conditions). Follow the kit instructions exactly; mailing delays after the test ends can affect results.
For real estate transactions, EPA’s Protocols for Radon Measurements in Homes specifies how to conduct testing during the inspection contingency period. Most Front Range home inspectors offer radon testing as an add-on service to their general inspection, using continuous radon monitors (CRMs) that produce a 48-hour reading. Cost: typically $125 to $200 added to the inspection. The companion guide on radon testing as part of home inspection covers this scenario.
What homeowners commonly get wrong about testing
Three common mistakes. First, testing in the wrong location — placing the kit on the main floor when the basement is the lowest occupied level. Result: under-reporting of the actual exposure level for occupants who spend time downstairs. Second, opening windows during the test — diluting the indoor radon and producing artificially low readings. Third, testing only once and assuming the result is permanent. Radon levels vary seasonally (higher in winter when homes are tighter and stack effect is stronger) and can change over years as the home settles or the soil conditions shift.
What CDPHE offers Colorado homeowners specifically
CDPHE sells discounted short-term test kits (typically $15) through its radon program. The kits are mailed to homeowners, deployed for the test period, and mailed back to a state-contracted lab for analysis. Results return in 7 to 14 days. CDPHE also publishes county-level radon data showing the percentage of tested homes exceeding the EPA action level. Boulder, Jefferson, El Paso, and several other Front Range counties consistently show more than 50 percent of tested homes above 4.0 pCi/L.
The cost-benefit of mitigation
Mitigation by ASD typically costs $1,200 to $2,500 on the Front Range and runs at approximately $10 to $30 per year in electricity. For a home that tested at 10 pCi/L pre-mitigation and is reduced to below 1 pCi/L post-mitigation, the lifetime reduction in cumulative WLM exposure for the occupants is substantial. EPA cost-effectiveness analyses consistently rate residential radon mitigation among the most cost-effective lifesaving interventions on a dollars-per-life-saved basis, comparable to seatbelts and smoke detectors. The companion guide on radon poisoning effects covers the long-term risk math.
Common questions homeowners ask after testing
“My test result was 3.9 pCi/L — am I in the clear?” EPA’s action level is 4.0 pCi/L, but the agency also notes that there is no safe lower threshold for radon. Consider mitigation for results between 2 and 4 pCi/L. World Health Organization recommends action at 2.7 pCi/L. “Should I retest if the first result was high?” Yes — confirm with a long-term test or a second short-term test before committing to mitigation. “Does the result change in winter?” Often yes — winter levels are typically higher due to tighter homes and stronger stack effect. Test in winter for the most conservative reading.
Why basement bedrooms warrant particular attention
Many Front Range homes use the basement as a primary bedroom — particularly in pre-1980 ranches where the basement was finished after construction. The occupant in a basement bedroom spends 8 hours per night breathing the air at the lowest occupied level, where radon concentrations are typically highest. Time-weighted exposure for a basement-bedroom occupant can exceed that of an upstairs occupant in the same home by a factor of two or more, even though both are exposed to the same range of indoor air.
References
- EPA Health Risk of Radon — U.S. Environmental Protection Agency
- CDC Radon page — Centers for Disease Control and Prevention
- American Lung Association on radon — American Lung Association
- CDPHE radon program — Colorado Department of Public Health and Environment
Frequently asked questions
What are the symptoms of radon gas in my home?
There are no acute symptoms. Radon is odorless, colorless, tasteless, and undetectable to all five senses. Homes with very high radon levels feel identical to homes with no radon. The only way to know whether radon is present is to test. Per EPA and Surgeon General, the only health effect is long-term lung cancer risk after years to decades of exposure.
Can I tell if my home has radon by how I feel?
No. Symptoms cannot substitute for testing. If you have acute respiratory symptoms, the cause is something other than radon — possibly viral or bacterial infection, allergies, carbon monoxide, mold, or another medical condition. See a physician for symptoms. Test the home with a certified test kit or professional measurement to know about radon.
How long does radon take to cause lung cancer?
Years to decades. EPA and CDC characterize radon lung cancer risk as cumulative across long-term exposure, with most cancers appearing after 5 to 25+ years of exposure. There is no single exposure event. Higher concentrations and longer durations increase risk. Mitigation reduces future risk substantially.
What should I do if I am worried about radon?
Test the home. Short-term test kits cost $15 to $50 and are available from hardware stores or CDPHE for Colorado residents. If results are above EPA action level of 4.0 pCi/L, hire a certified radon mitigation contractor — Front Range pricing typically runs $1,200 to $2,500 for active soil depressurization.
Front Range homeowners who want a connection to a certified radon measurement professional or mitigation contractor can reach out through our contact page.
Test your home for radon
Radon is invisible and odorless, so a test is the only way to know your level. A short-term kit gives a first reading in days; a digital monitor tracks it over time.
| Product | Why | Buy |
|---|---|---|
 AirChek Charcoal Radon Test Kit | Lab fee usually included; EPA short-term protocol. | Amazon — $21.95 |
 First Alert RD1 Radon Test Kit | Widely stocked; 48-hour charcoal test. | Amazon — $16.98 |
 Airthings Corentium Home | Digital monitor with a long-term average. | Amazon — $147.14 |