Radon is one of the few home hazards you cannot see, smell, or taste, which is what makes it so easy to overlook. It rises naturally from the soil and rock beneath your house, slips in through small openings in the foundation, and can build to harmful levels without a single warning sign. Most families have no idea it is there until they test for it.
The EPA considers a dangerous radon level to be anything at or above 4 picocuries per liter, written as pCi/L. It recommends fixing any home that reaches that mark and suggests acting even below it, since no amount of radon is completely safe. The sections below break down what each level means and what to do about it.
What Is Radon?
Radon is a radioactive gas produced when uranium in soil, rock, and water breaks down over time. Because it forms underground, it constantly seeps upward and can collect inside any building that sits on top of it.
The gas enters through cracks in the foundation, gaps around pipes, sump pits, and openings in crawl spaces. Once inside, it has nowhere to escape and concentrates in the lower levels of the home. Breathing it in over months and years is what raises the health risk, which is why understanding your level matters so much.
How Radon Is Measured?
Radon is measured by how much radioactivity it gives off in a set volume of air. Two units are common, depending on where you live:
- pCi/L (picocuries per liter): The standard unit used in the United States.
- Bq/m³ (becquerels per cubic meter): The unit used in most other countries, where 1 pCi/L equals about 37 Bq/m³.
For perspective, the average indoor radon level in American homes is about 1.3 pCi/L, while outdoor air averages around 0.4 pCi/L. Those baselines help put any test result in context.
What Radon Level Is Considered Dangerous?
No radon level is considered completely safe, since the risk rises gradually with every increase in concentration. Still, health agencies use clear benchmarks to mark the point where action becomes important.
The EPA Action Level of 4 pCi/L
The EPA sets its action level at 4 pCi/L, which is the threshold where fixing the home is strongly advised. Reaching or passing that number signals that radon has built up enough to warrant a mitigation system. The agency recommends mitigation at 4 pCi/L or higher and also advises homeowners to consider acting between 2 and 4 pCi/L, since meaningful risk still exists below the official line.
What Each Radon Level Means
Reading a radon result is easier when you know what each range signals. Here is a simple guide to what the numbers mean:
- Below 2 pCi/L: Lower risk and no action required, though reducing it further is still beneficial.
- 2 to 4 pCi/L: A gray zone where the EPA suggests considering mitigation.
- 4 pCi/L and Above: The EPA action level, where fixing the home is recommended.
- 10 pCi/L and Above: A high reading that calls for prompt mitigation.
- 20 pCi/L and Above: A very high level that should be addressed as soon as possible.
The higher the number, the more urgent the response, but any result above the action level deserves attention rather than delay.
How the US and WHO Thresholds Compare
The United States is not the only authority with a radon benchmark, and the international standard is stricter. The World Health Organization recommends a reference level of 100 Bq/m³, which works out to roughly 2.7 pCi/L and sits well below the EPA’s 4 pCi/L. The WHO also estimates that radon causes between 3 to 14% of all lung cancers in a country, depending on average radon levels and smoking rates. The takeaway across both standards is the same, which is that lower is always better.
Why Is Radon So Dangerous to Your Health
The danger of radon is not immediate, which is part of what makes it so serious. The risk comes from long-term exposure that quietly damages lung tissue over the years. The EPA estimates that radon causes about 21,000 lung cancer deaths in the United States each year, making it the second leading cause of lung cancer after smoking.
The reason it carries such weight comes down to a few clear facts:
- Radon is the top cause of lung cancer among people who have never smoked.
- The damage builds silently over the years, with no early symptoms to warn you.
- Every home in every state can be affected, regardless of age or construction.
Why Does Exposure Time and Smoking Multiply the Risk?
Two factors raise radon risk more than any others, which are how long you are exposed and whether you smoke. The longer radon sits in your home at an elevated level, the more your cumulative exposure adds up. Smoking makes things far worse, since the combination of tobacco and radon damages the lungs in ways that multiply rather than simply add together. For a smoker living with high radon, the risk climbs sharply compared to a nonsmoker in the same home.
How Do You Find Out Your Radon Level?
Testing is the only reliable way to learn your radon level, since you cannot detect the gas with your senses. The process is simple, affordable, and quick to arrange.
Here is how radon testing usually works:
- Short-Term Test: A small device sits in the lowest occupied level of the home for two to seven days to give a fast snapshot.
- Long-Term Test: A detector stays in place for more than 90 days to capture a more accurate year-round average.
- Professional Measurement: A certified tester places calibrated equipment and follows proper placement and timing standards.
- Lab Analysis: The device or data is analyzed to produce a clear pCi/L reading you can act on.
- Confirmation Retest: A second test confirms a high result before any mitigation work begins.
Greenhorn Breckenridge handles the entire testing process with professional precision, so you don’t have to worry. Our certified team places the test correctly, reads the results the right way, and explains in simple terms what your number means for your family and your home.
Testing is the only reliable way to know if this invisible, radioactive gas is reaching dangerous levels inside your home. Call us today to schedule a certified test and get the definitive, lab-backed peace of mind you deserve.
What to Do If Your Radon Level Is High?
High radon results are not a reason to panic, because radon problems are very fixable. Once we confirm a high reading, we help you understand it and plan the right next step.
Proven mitigation methods can bring even very high levels back down to a safe range. The common fixes we walk homeowners through include:
- Sub-Slab Depressurization: A vent pipe and fan pull radon from beneath the foundation and release it safely outside.
- Sealing Entry Points: Closing cracks and gaps in the foundation limits how much radon works its way in.
- Improving Ventilation: Increasing airflow in basements and crawl spaces helps dilute the gas.
- Retesting After Mitigation: We run a follow-up test to confirm the system worked and the level has dropped below the action threshold.
Most systems are affordable and highly effective, and our team makes sure you walk away with cleaner air and real peace of mind.
Is a radon level of 2 pCi/L dangerous?
Radon at 2 pCi/L sits below the EPA action level, so mitigation is not required. Some risk still exists at that reading, which is why the EPA suggests considering action anywhere between 2 and 4 pCi/L.
How high is too high for radon?
Any reading at or above 4 pCi/L is high enough to act on, and anything past 10 pCi/L is considered seriously elevated. The higher the number climbs, the sooner mitigation should happen to lower your long-term exposure.
Can you get rid of radon completely?
You cannot remove radon entirely, since trace amounts exist in nearly all air. Mitigation systems can lower indoor levels dramatically, often well below the action level, which makes the remaining risk very small for your household.
How often should I test for radon?
Testing every two years is a good habit for most homes, and you should always test after buying a property or completing major renovations. Retesting also confirms that any mitigation system is still working properly.
Does opening windows lower radon levels?
Opening windows can lower radon briefly by letting the gas escape, but the effect disappears as soon as you close them. It is a short-term fix at best and never a substitute for proper mitigation.
Conclusion
Radon is dangerous precisely because it gives no warning, so the only way to know your level is to test for it. The EPA action level of 4 pCi/L is the benchmark to watch, but lower readings still carry some risk, and higher ones call for prompt action. Knowing your number is the first and most important step toward protecting your household.
Your home’s radon level is one number you should never leave to chance. Greenhorn Breckenridge LLC has been testing properties across Kern County since 2020, and we keep the whole process quick, certified, and clear from start to finish.
Call (888) 890-1313 to book your radon test, and if the result comes back high, we will guide you straight to the next step.
