How High Is Too High? Understanding the EPA Radon Action Level

Radon is an invisible, odorless gas that can seep into your home from the soil beneath the foundation. While all homes have some level of radon, it’s the concentration that matters. So how high is too high when it comes to radon? And what should Cedar Rapids homeowners do if their levels are higher than recommended?
​
In this article, we’ll break down the EPA radon action level, what it means for your home, and how to take action if your radon levels exceed safe limits.

What Is the EPA Radon Action Level?

The U.S. Environmental Protection Agency (EPA) has established a radon action level of 4 picocuries per liter (pCi/L) of air. If your home’s radon measurement is at or above this level, the EPA recommends taking steps to reduce it.

​But that doesn’t mean levels below 4 pCi/L are completely risk-free. Radon exposure is linked to lung cancer even at lower levels — and the risk increases the higher the radon concentration in your home.

Why 4 pCi/L?

The EPA action level isn’t a strict threshold of safety vs. danger. Instead, it’s a practical guideline that balances health risk with cost and feasibility of mitigation. Here’s what it represents:

• At 4 pCi/L, a homeowner's lifetime risk of lung cancer increases significantly compared to someone living at outdoor radon levels.
  
  
• The EPA chose 4 pCi/L because mitigation systems can reliably reduce levels below this point in most homes.
  
  
• Even at 2–4 pCi/L, the EPA still encourages action where practical — especially for families with smokers or high-risk individuals.
  

Is Any Radon Level Safe?

No. There is no known safe level of radon. Radon is a radioactive gas, and even low exposures contribute to cumulative health risks over time. The goal of radon mitigation is to reduce levels as low as reasonably achievable — not just below a specific number.
​
That said, the higher the level, the greater the urgency.
​

How Radon Levels Are Measured

Radon testing can be short-term (2–7 days) or long-term (90 days or more). Here’s how results are typically reported:

• Below 2 pCi/L: Lower risk, but retesting can still be a good idea.
  
  
• 2–4 pCi/L: Moderate risk — consider retesting or mitigation.
  
  
• 4 pCi/L or higher: Strongly recommended to take action.
  
  
  

Because radon levels can change with seasons and weather patterns, long-term testing provides the most accurate picture of your home’s average radon concentration.

What to Do If Your Levels Are High

If your radon test shows levels at or above 4 pCi/L, here’s what you should do:
1. Confirm With a Second Test
A second test — especially a long-term one — helps confirm whether high levels are persistent.

2. Contact a Professional Radon Mitigation Contractor
A qualified radon professional can assess your home and install a mitigation system tailored to your needs.

3. Seal Foundation Cracks and Gaps
Though not a standalone solution, sealing obvious entry points improves overall performance.

4. Retest After Mitigation
​Once a system is installed, testing again confirms that radon levels have dropped to safe levels.

​

Radon Levels in Cedar Rapids Homes

Homes in Cedar Rapids, like many areas of Eastern Iowa, can experience elevated radon levels due to local soil composition. That’s why testing every home — regardless of age or type — is crucial.
​
Even newly constructed homes with modern building techniques can trap radon inside if the gas isn’t properly vented.

Final Thoughts

Understanding the EPA radon action level helps you make informed decisions about your home’s indoor air quality. While 4 pCi/L is the official action threshold, any elevated radon level deserves attention, especially in areas known for higher radon potential like Cedar Rapids.
​
Testing is the only way to know your home’s radon level. If your results are high, professional mitigation can protect your family and give you peace of mind.

​