Milwaukee, WI Homes and the Truth About Radon Risk

Radon is not limited to a few isolated neighborhoods or rural areas. It can affect homes across Milwaukee, WI and throughout Wisconsin, including older houses, newer construction, homes with basements, and buildings without them. The only reliable way to know whether a particular home has elevated radon is to test that home.

Why does radon vary from one area to another?

Radon forms naturally as uranium in soil and rock breaks down. Because soil composition, geology, drainage, foundation design, and construction practices differ from place to place, some areas have a greater potential for elevated indoor radon than others.

That geographic pattern is useful for public health planning, but it does not predict the radon level in an individual house. The U.S. Environmental Protection Agency explains that elevated radon has been found in all three national radon zones and that zone maps should not be used to decide whether a home needs testing. ([epa.gov](https://www.epa.gov/radon/epa-map-radon-zones-0?utm_source=openai))

In Wisconsin, state health officials also caution that homes with elevated readings can be located very close to homes with lower readings. A neighborhood map may show a general trend, but it cannot confirm the conditions inside a specific building. ([dhs.wisconsin.gov](https://www.dhs.wisconsin.gov/radon/index.htm?utm_source=openai))

Can a home in Milwaukee have high radon even if nearby homes do not?

Yes. Radon levels can differ substantially between neighboring houses.

Several details can create different results from one property to the next:

• Cracks or openings in the foundation
• Gaps around utility lines, floor drains, or sump pits
• Soil contact beneath a basement or slab
• Differences in foundation materials and construction
• Air pressure inside the building
• How often windows and doors are opened
• Whether the lower level is finished or regularly occupied

A neighbor’s test result is therefore not a substitute for testing. A nearby result may provide local context, but it cannot show what is happening inside another home. The EPA specifically identifies this as a common misconception. ([epa.gov](https://www.epa.gov/sites/default/files/2016-12/documents/2016_a_citizens_guide_to_radon.pdf?utm_source=openai))

This is especially relevant in a city with a mix of older housing, remodeled lower levels, additions, and newer construction. Changes made during renovations may alter airflow or create new pathways between the soil and indoor living areas.

Are older homes more likely to have a radon problem?

Not necessarily. Older homes may have settling cracks, aging floor drains, or foundation openings that allow soil gas to enter. However, newer homes can also have elevated radon.

A tightly sealed, energy-efficient home may reduce natural air exchange. During cold weather, households often keep windows closed and spend more time indoors, while heating systems and indoor air pressure can influence how soil gases move through a structure.

The EPA states that radon can affect old and new homes, drafty and well-sealed homes, and homes with or without basements. Building age alone does not establish the risk. ([epa.gov](https://www.epa.gov/radon/how-does-radon-get-your-home?utm_source=openai))

Does a basement automatically mean high radon?

No. A basement can provide more direct contact with soil, which may create more opportunities for radon entry, but the presence of a basement does not guarantee an elevated reading.

Radon can also enter through homes built over crawl spaces or concrete slabs. Lower levels are usually tested first because they are closest to the ground and may have the highest potential for exposure. The test should be placed in the lowest level that is regularly used or could reasonably be used as living space.

A basement used only for storage may not represent the same exposure conditions as a finished room used as a bedroom, office, or recreation area. Testing decisions should account for how the household actually uses the building.

Does Wisconsin’s radon map tell residents whether testing is necessary?

No. A radon potential map can identify broad areas where elevated readings may be more common, but it cannot clear a particular property of risk.

Wisconsin’s Department of Health Services recommends testing every home and building because local results can vary significantly, even over short distances. The agency describes testing as the only way to determine whether a property has a radon exposure concern. ([dhs.wisconsin.gov](https://www.dhs.wisconsin.gov/radon/index.htm?utm_source=openai))

Maps are most useful for education, building practices, and directing public resources. They should not be treated as a replacement for a test.

What kind of test should a household use?

A short-term test is commonly used for an initial screening. Depending on the device, it may remain in place for several days. The test should be placed in the lowest lived-in level, away from drafts, high heat, direct sunlight, and areas with excessive moisture.

For reliable results, follow the device instructions carefully. During a test, unusual ventilation, open windows, fans, or other conditions can affect the measurement.

If the initial result is near or above the EPA action level of 4.0 picocuries per liter, follow-up testing helps determine whether the elevated reading is persistent. Wisconsin guidance commonly recommends a longer-term test for many results between 4.0 and 8.0 pCi/L, while a second short-term test may be appropriate for higher initial readings. ([city.milwaukee.gov](https://city.milwaukee.gov/health/information/environmental-health/radon-Information?utm_source=openai))

What does a result of 4.0 pCi/L mean?

A result of 4.0 pCi/L or higher is the EPA level at which reducing radon is recommended. It is not a dividing line between “safe” and “unsafe,” because radon risk decreases as exposure decreases and no level is considered completely risk-free.

A lower result does not necessarily mean the property will always remain at that level. Radon concentrations can change with season, weather, ventilation, soil conditions, foundation changes, and household use.

For that reason, a home with a low result may still be retested periodically, especially after a major renovation, a change in lower-level occupancy, or a significant alteration to the foundation or ventilation system. ([epa.gov](https://www.epa.gov/radon/epa-map-radon-zones-0?utm_source=openai))

Does winter weather affect radon testing?

Seasonal conditions can influence indoor radon readings. In colder months, windows and doors are generally closed, heating systems operate more often, and pressure differences between the house and the soil may increase. These conditions can draw more soil gas indoors.

That does not mean testing during another season is useless. A properly conducted test provides valuable information about the home during the period measured. If the result is unexpectedly high, borderline, or inconsistent with earlier testing, a longer-term test can provide a better picture of average exposure.

For households in Milwaukee, winter is often a practical time to test because lower levels may be occupied more regularly and ventilation habits are more consistent.

Do homes without basements need testing?

Yes. Homes built over slabs and crawl spaces can also have radon concerns. Entry points may include cracks in concrete, joints between walls and floors, crawl-space openings, plumbing penetrations, and gaps around utility connections.

The EPA recommends testing all homes, regardless of foundation type or construction age. Radon can also enter through private well water in some circumstances, although soil gas is the primary source of most indoor radon problems. ([epa.gov](https://www.epa.gov/radon/how-does-radon-get-your-home?utm_source=openai))

What should residents remember?

Radon is a location-influenced problem, but it is not confined to a few locations. Regional geology can raise or lower the general potential, yet individual building conditions determine how much radon enters and accumulates indoors.

For local households, the practical message is straightforward:

• A low-risk map area does not eliminate the need for testing.
• A nearby elevated test does not prove that every home has the same result.
• A new, remodeled, sealed, or basement-free home can still have radon.
• Testing the lowest regularly occupied level is a sensible starting point.
• Results at or above 4.0 pCi/L generally call for follow-up and consideration of radon reduction.

The question is not whether a neighborhood is labeled a “radon area.” The useful question is whether the specific home has been tested under proper conditions.