Radon Gas in Homes - How Radon Enters Homes and Why You Can’t Smell It

Your home looks spotlessly clean. There’s no mold or indoor air contaminant that triggers your allergies. Even your asthma has eased up over the years. And you finally breathe easier, relieved that your IAQ is nearly perfect. But you might have overlooked a sneaky but dangerous contaminant: radon gas in homes.

Many homeowners don’t think to test for radon gas because it doesn’t cause any immediate symptoms. So, even when concentrations are above the usual radon safety levels, this radioactive gas may not cause any immediate health issues. Its true impact is only felt years later. 

But how does the radon enter homes? What are the common radon entry points? And why is it impossible to detect radon through sight or smell? Let’s find out the answers to these questions. 

What is Radon Gas and Where Does it Come From?

Radon is a naturally occurring radioactive gas. It forms when uranium and radium in soil, rocks, and other materials break down. Today, it is present in almost every type of land and geography, meaning that no neighborhood or region is completely radon-free. 

The EPA’s map of radon zones across the country proves this. 

Most zones have radon levels above 2 pCi/L. In many zones, the concentration exceeds the recognized radon safety level of 4 pCi/L. 

The troubling part is that no matter which zone you look at, radon doesn’t remain in the soil. It can seep up through the ground and find its way into homes through various radon entry points.

Why You Can’t See, Smell, or Taste Radon?

Radon levels are widely recorded and studied. Still, many homes in the US continue to remain vulnerable to radon exposure risks. The numbers have consistently revealed this weakness.

  • 2013: News in Health reported that around 1 in 15 homes in the US had high radon levels.
  • 2017: The National Library of Medicine published a study showing that in homes built in or after 1992, radon levels were 31.5% higher than in older homes.
  • 2019: Nature found, from a survey of over 11,000 homes, that radon exposure was steadily increasing, no matter the season. 
  • 2025: Research from Harvard’s School of Public Health found that over 83 million Americans — making up around a quarter of the country’s population — may be exposed to the gas in concentrations above the usual radon safety levels.

Why is radon exposure so common and easy to ignore? The answer lies in the gas itself.

  • Radon is completely invisible to the naked eye. 
  • It is odorless, so you cannot sniff out the radon gas in homes.
  • The gas also has no taste, so you cannot detect its presence in your water.
  • And when you cannot see, smell, or taste something, it is easy to assume that it is not present at all. This is what makes radon uniquely dangerous. 

Most household hazards offer some signs or indicators. A gas leak has an odor, mold is usually visible, and dust or pollen triggers allergies. But radon gives you no signals. It is a silent killer that builds up in your indoor air.

The only option is testing. Radon testing is the only way to know if it’s present. 

So, don’t put off this crucial step in making your home safe for yourself and your family. 

Schedule a radon testing appointment with InHaus Lab, and we’ll get back to you with a quote in just 30 minutes.

At InHaus Lab, we’ve tested over $100 million worth of homes in and around Aspen, Vail, Denver, and Minneapolis. We can help you, too. 

How Radon Becomes a Health Risk

Radon doesn’t cause any symptoms right away. You could be exposed to it for months or even years, and still feel absolutely normal. But just because you feel perfectly fine, doesn’t mean the radon exposure risks aren’t real.

The EPA outlines these risks clearly:

  • Radon is the second leading cause of lung cancer in the US. 
  • For non-smokers, it is the number one cause of this cancer.
  • Every year, the gas causes around 21,000 lung cancer-related deaths.

While exposure to radon gas in homes may cause no immediate symptoms, this dangerous gas steadily damages the body. Here’s how:

  • Radioactive Decay: Radon decays into radioactive particles that remain in the lung tissues

  • Cell Damage: These particles emit radiation that damages the lung cells over time

  • Cell Mutation: Damaged lung cells can mutate and develop into lung cancer

  • Noticeable Symptoms: Lung cancer symptoms appear much later, once the disease has progressed 

The Many Ways in Which Radon Can Enter Your Home

Its inherent properties make radon gas detection almost impossible manually. But that’s not all. Radon can also find its way into homes very sneakily. There are many radon entry points that homeowners should be aware of.

  • Cracks in the Basement

Your basement is the part of your home that’s closest to the soil, and the soil is the primary source of this gas. If there are any cracks in the floors or walls of your basement, radon can easily sneak in. 

It doesn’t matter how small the gap is. Even a tiny sliver of an opening is enough for radon to get in. 

  • Gaps Around Pipes

Every pipe that enters your home has to pass through the foundation. This includes water, gas, and electrical pipes. If the spaces around these pipes aren’t properly sealed, they might become radon entry points.

These gaps are easy to overlook because they're usually hidden behind walls or in utility areas. But even a small unsealed gap around a pipe can let in a significant amount of radon over time.

  • Crawl Spaces With Exposed Soil

Crawl spaces also offer easy entry points for radon gas into homes. They sit directly above the ground. With no barrier between the soil and the air inside, radon can freely rise and accumulate in the area beneath your floors.

From there, it can move up through tiny openings and gaps into the rest of your home. This increases the radon exposure risks in your living space.

  • Crawl Space Vents

Crawl space vents are designed to allow air circulation and prevent moisture buildup. But if the surrounding soil has high levels of radon, these vents can pull the gas directly into the crawl space. 

And once radon finds its way in through the vents, it follows the same path you saw earlier. It moves up from the crawl space through the floor and into your living areas.

  • Floor Drains in the Basement

Floor drains in the basement connect directly to the ground below. These open pipes can become channels through which radon travels up from the soil with very little resistance. Once it gets into your basement, radon can easily find its way into the rest of your home. 

Many homeowners never think twice about the floor drains. But if it’s unsealed or rarely used, it could be one of the most active radon entry points in your home.

  • Sump Pump Pits

A sump pit is dug directly in the ground below the basement. This means it gives your home a direct connection with the soil. And if that soil is radon-rich, the sump pit gives the gas an unrestricted pathway into your home. 

That’s why you should always seal the pit with an airtight cover. This simple step can cut off one of radon’s most direct entry points. 

  • Well Water

Radon can also enter your home through your water supply, especially if you rely on a private well. Unlike municipal water supplies, which are regularly treated and monitored for contaminants, private well water testing is often the homeowner’s responsibility.

Still, according to the EPA, more than 43 million people in the US use water from private wells.

When these people use untested or poorly tested water from private wells, they may be exposed to high levels of radon. In this post from Reddit, a user explains exactly one such instance where they found that their well water had extremely elevated radon levels. 

  • HVAC Ducts

Your HVAC system circulates air throughout your home. But if radon has already entered your home at the basement or ground level, the HVAC ducts may distribute it to every room in the house. 

This means radon exposure risks will no longer be limited to your basement or crawl space. The gas can end up in your bedroom, living room, or your child’s room, carried there by the very system meant to keep your home comfortable. 

  • Granite Countertops

Granite is a naturally occurring rock. Like soil and minerals, it contains trace amounts of uranium. And you know what happens when that uranium breaks down. This is why granite can also be a source of radon gas in homes.

To be clear, though, the levels from this source are generally much lower than what seeps in through the foundation. But in a poorly ventilated space, even trace amounts can add up. 

Know if Your Home is Safe With Professional Radon Testing 

There are so many radon entry points that you may accidentally ignore one or more such gaps. If you don’t notice any obvious cracks or openings, you might think your indoor air is safe. But at best, that’s only a guess. And at worst, it could lead to severe health issues later. 

Testing is the only real way to know for sure if your home is safe.

If you haven’t had your home checked for radon, now may be a good time to find out if this gas is circulating indoors. 

Get in touch with InHaus Lab today and book your appointment for radon testing services.

Radon Gas in Homes FAQs

  1. Is DIY radon gas detection possible?

Yes, you can buy affordable radon test kits at hardware stores. But if you want more accurate and reliable results, choose professional radon testing. 

  1. What are the radon safety levels for indoor air?

The EPA recommends fixing your home if radon levels are 4 pCi/L or higher. That said, it is also worth taking action if the levels are between 2 and 4 pCi/L. 

  1. Are homes radon-proof in 2026? 

Many new buildings include radon-resistant features. But you still need to test your home to be absolutely sure. No home is guaranteed to be safe without testing, because radon’s entry points are easy to miss.

  1. What are some commonly overlooked radon entry points? 

Radon can sneak into your home through the crawl space, floor drains, gaps around your pipes, and even your water supply. 

  1. Should I worry about radon exposure risks if I don’t live on the ground floor?

If you live on a higher floor, the risk is reduced but not entirely gone. Radon can still accumulate in your home, especially if the space is poorly ventilated. 

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