City Cast Philly logo

Should we be worrying about radon in Philly?

Posted on January 23, 2025   |   Updated on January 28

Siani Colón

A white air quality monitor indicates a radon level of 0.5

A screen on an air quality monitor in Lafayette, Ca., indicating the radon level. (Gado / Getty Images)

January is National Radon Action Month, when the U.S. Environmental Protection Agency encourages residents to test their homes for the gas. In Pennsylvania nearly 40% of homes have radon levels above the EPA’s guidelines. But what exactly is radon and why does it matter?

What is radon?

Radon is an odorless, tasteless, radioactive gas. According to the World Health Organization, radon is produced by the decay of uranium, which is found in rocks and soils. When radon escapes into the air more radon particles are produced as it decays further, contaminating airways. It can enter inside buildings through cracks in the foundation. While radon concerns are primarily airborne, it has been found in drinking water as well. Pennsylvania’s geology, climate, and natural gas wells contribute to radon’s presence in the state. Research has also linked fracking to the increase of the gas in homes.

Why can radon be dangerous?

Because of the gas’ odorless, tasteless nature, it may be difficult to identify whether your home or building is contaminated with radon. Radon is the second leading cause of lung cancer behind smoking, according to the American Lung Association. If you smoke and are also regularly exposed to radon, that puts you at even greater risk of lung cancer. About 21,000 people who were exposed to radon die from lung cancer each year, including 2,900 who were nonsmokers. Radon levels measured above 4 picocuries per liter (pCi/L) are considered cause for concern.

How much radon is in Philadelphia?

This map of radon zones identifies which Pennsylvania counties have the highest potential for radon risk. Philadelphia is designated as Zone 3, the lowest risk level, while surrounding Bucks, Montgomery, Chester, and Delaware counties are Zone 2. The EPA still emphasizes individual testing of buildings for radon risk, no matter the zone designation.

You can use this tool to check the reporting of radon levels by ZIP code. For example although the average level of radon inside basements in the 19134 ZIP code (Kensington, Port Richmond) was recorded at 1.9 pCi/L, the max result was 112.4 pCi/L, way above guidelines.

How can I protect myself?

There are several measures you can take to protect yourself from radon:

  • Request a free test kit from the American Lung Association, or purchase a test kit from a hardware or home improvement store.
  • Find certified testers through the state’s Department of Environmental Protection.
  • If high levels are confirmed in your building, hire a professional to seal any cracks and install a radon mitigation system.
  • Join the Reducing Outdoor Contaminants in Indoor Spaces' next Low Cost Monitoring Project cohort. Although it primarily targets Southwestern Pennsylvanians, ROCIS accommodates a limited number of Pennsylvanians outside that region.
see more:public health

Share article

Hey Philly

Stay connected to City Cast Philly and get ready to join the local conversation.

Can't subscribe? Turn off your ad blocker and try again.

Philly, Explained

See All

The latest in Philly

Sponsored

Moving to Philadelphia? What to Check Before You Pick a Neighborhood, Book a Truck, and Sign a Lease

With this guide, you can move to Philadelphia, move from another place to Philadelphia, or just see if living in Philadelphia fits your d...

Wellknown Moving Company Logo
Food & DrinkJune 4

Grab Summer Produce at These Farmers Markets

It’s the time of year to start stocking up on summer favorites like berries. Find the freshest crops at your local market.

Boxes of blueberries, raspberries, and blackberries
Philly's BestJune 2

How to Spend June 2026 in Philly

Wander Philly’s museums, pick fresh fruit, and celebrate the solstice throughout the month.

Drummers perform in Old City during Pride March
Philly Life HacksJune 2

Where To Take Swimming Lessons in Philly

Don’t just sit poolside all summer. Learn to splash in the water safely by taking these foundational swim classes.

Swimmer does a lap in a pool
Philly HistoryJune 1

The First Successful Sit-In for LGBTQ+ Rights Was in Philadelphia

The act of civil disobedience against discrimination occurred before the more widely known Stonewall Riots, which are considered the cata...

A marker at the former 17th Street location of Dewey’s stands at 219 S. 17th St. (Siani Colón / City Cast Philly)
Food & DrinkMay 28

Your Guide to New Restaurants, Bars and Cafés in Philly

Philly’s local culinary scene is constantly growing and changing. Here’s a recap of some of the restaurants, bars, cafés, and other delic...

Bowls of loaded jacket potatoes
Philly's BestMay 21

Ride a Bike and Make a Friend at These Philly Biking Clubs

Why bike solo when you can join a community that also loves exploring the city on two wheels?

Zoomed in shot of yellow bicycle and its spokes
Philly HistoryMay 19

Who Is Ona ‘Oney’ Judge?

A new holiday honors one woman’s brave escape to freedom even as there are efforts to erase that history.

Names on a stone wall: Austin, Paris, Hercules, Christopher Sheels, Richmond, Giles, Oney Judge, Moll, Joe