Denver Dampness: AC Lies Hiding Radon Lung Risk?

By Franklin Everett Shaw

February 3, 2026

Imagine stepping into your Denver home on a sweltering summer day, the cool blast of air conditioning a welcome relief. But what if that very comfort system was silently drawing in a hidden danger: radon gas? Denver’s unique geological makeup, combined with common basement construction and the mechanics of air conditioning, creates a perfect storm for radon infiltration. This invisible, odorless gas is a leading cause of lung cancer, and understanding how your AC contributes to the problem is crucial for protecting your health and your family.

Radon, a naturally occurring radioactive gas, is a significant concern in Denver due to the area’s soil composition. The Front Range, where Denver sits, is rich in uranium, which decays into radium, and then into radon. This gas seeps up from the ground and can enter homes through cracks in foundations, gaps around pipes, and other openings. Denver’s older homes, many with basements, are particularly vulnerable. Basements, being underground, are in direct contact with the soil and often have less ventilation, allowing radon to accumulate.

Now, consider your air conditioner. When it runs, it creates negative pressure inside your home. This means the air pressure inside is lower than the air pressure outside. To equalize the pressure, air is drawn in from the outside, and unfortunately, this includes air from the soil surrounding your foundation, potentially carrying radon gas with it. The longer and more frequently your AC runs, the greater the negative pressure and the higher the risk of radon infiltration. This is especially true in older homes with leaky ductwork, as the AC system struggles to maintain the desired temperature, leading to prolonged operation.

So, what can a Denver homeowner do? The first step is testing. Don’t rely on assumptions; know your radon levels. DIY radon test kits are readily available at hardware stores like Home Depot or Lowe’s in the Denver area, or online. These kits typically involve placing a collection device in the lowest level of your home for a specified period (usually 2-7 days) and then sending it to a lab for analysis. Follow the instructions precisely. A common mistake is placing the test kit near a window or door, which can skew the results. Place it in a frequently used room, away from drafts and direct sunlight.

For a more comprehensive assessment, consider hiring a certified radon measurement professional. In Denver, you can find qualified professionals through the Colorado Department of Public Health and Environment (CDPHE) website. They use specialized equipment to conduct both short-term and long-term tests, providing a more accurate picture of your home’s radon levels. Short-term tests are useful for a quick assessment, while long-term tests (90 days or more) provide a better average radon concentration, accounting for seasonal variations.

If your radon levels are at or above the EPA’s action level of 4 picocuries per liter (pCi/L), mitigation is recommended. Don’t panic; radon mitigation is a common and effective process. The most common mitigation method is soil suction, which involves installing a vent pipe and fan to draw radon gas from beneath the foundation and vent it safely outside. The system creates a slight vacuum under the slab, preventing radon from entering the home.

Choosing a qualified radon mitigation professional is crucial. Again, the CDPHE website is your friend. Look for certified mitigators with experience in Denver’s specific soil conditions and housing types. Get multiple bids and ask for references. A reputable mitigator will conduct a thorough inspection of your home to identify the best mitigation strategy and provide a detailed proposal.

Now, let’s address the air conditioning aspect. While you can’t eliminate the negative pressure entirely, you can minimize it and improve your home’s energy efficiency, which indirectly reduces radon infiltration.

Here are some actionable steps:

• Seal cracks and openings: Caulk and seal any cracks in your foundation, around pipes, and in other areas where radon could enter. This is a simple and cost-effective way to reduce radon infiltration. Pay special attention to the area where the foundation meets the walls.
• Improve ventilation: Ensure adequate ventilation in your basement. Consider installing a radon mitigation system with a sub-slab depressurization system, which creates negative pressure under the slab, preventing radon from entering the home. Even opening windows periodically can help, but this isn’t a practical solution during the summer months when the AC is running constantly.
• Optimize your AC system: Ensure your AC system is properly sized for your home. An oversized system will cycle on and off frequently, creating more pressure fluctuations. A properly sized system will run more consistently, reducing pressure variations.
• Consider an energy-efficient HVAC system: Upgrading to a high-efficiency HVAC system can significantly reduce your energy consumption and the amount of time your AC needs to run. Look for systems with a high SEER (Seasonal Energy Efficiency Ratio) rating.
• Install a heat recovery ventilator (HRV) or energy recovery ventilator (ERV): These systems bring fresh air into your home while exhausting stale air, helping to balance air pressure and improve indoor air quality. HRVs are better suited for colder climates like Denver, as they recover heat from the exhaust air to preheat the incoming fresh air. ERVs also recover moisture, which can be beneficial in dry climates.
• Regular HVAC maintenance: Ensure your HVAC system is properly maintained. Clean or replace air filters regularly to improve airflow and reduce strain on the system. A clogged filter can increase negative pressure. Schedule annual maintenance to ensure your system is running efficiently.
• Duct sealing: Leaky ductwork can significantly contribute to negative pressure. Have your ducts inspected and sealed by a qualified HVAC professional. This will improve the efficiency of your AC system and reduce radon infiltration.
• Monitor your radon levels: Even after mitigation, it’s important to monitor your radon levels periodically to ensure the system is working effectively. Consider purchasing a continuous radon monitor for real-time monitoring.

A common pitfall is neglecting to address the source of the radon. Simply running an air purifier won’t solve the problem; you need to prevent the radon from entering your home in the first place. Another mistake is assuming that mitigation is a one-time fix. Radon levels can fluctuate over time, so regular monitoring is essential.

Let’s consider a real-world scenario: A Denver homeowner in the Washington Park neighborhood notices a musty smell in their basement and suspects a radon problem. They purchase a DIY test kit and find that their radon levels are above the action level. They contact three certified radon mitigation professionals for bids. After reviewing the proposals and checking references, they choose a mitigator who recommends a sub-slab depressurization system. The system is installed, and follow-up testing confirms that radon levels have been reduced to below the action level. The homeowner also has their ductwork sealed and upgrades to a high-efficiency AC system to further reduce energy consumption and radon infiltration.

In conclusion, protecting your Denver home from radon requires a proactive approach. Test your home regularly, especially if you have a basement. If your radon levels are high, hire a qualified mitigation professional to install a mitigation system. And finally, optimize your air conditioning system to minimize negative pressure and improve energy efficiency. By taking these steps, you can breathe easier knowing you’ve taken steps to protect your health and your family from the dangers of radon gas. Don’t wait; take action today.