Published: April 15, 2025 | Closer Look Home Inspectors · InterNACHI Certified · Mankato, MN

Complete Radon Testing Guide for Mankato, MN

By Closer Look Home Inspectors | (507) 721-3820

Radon is the second leading cause of lung cancer in the United States, and Blue Earth County sits squarely in EPA Radon Zone 1, the highest risk classification. As Mankato's trusted home inspectors, we consider radon testing one of the most important services we provide. Here is everything you need to know.

What Is Radon?

Radon is a naturally occurring radioactive gas produced by the decay of uranium in soil and rock. It is invisible, odorless, and tasteless. Radon enters homes through cracks in foundations, gaps around pipes, sump pump openings, and any point where the building contacts the ground.

Why Mankato Has High Radon Risk

Blue Earth County's geology creates elevated radon potential:

• Glacial deposits: Southern Minnesota's glacial till contains uranium-bearing minerals that produce radon gas
• Soil composition: Clay-heavy soils can trap radon near the surface and channel it toward foundations
• EPA Zone 1: The entire county is classified as highest risk, with predicted average indoor levels above 4.0 pCi/L
• Statistics: Approximately 40% of Minnesota homes test above the EPA action level

Health Risks

The EPA estimates radon causes approximately 21,000 lung cancer deaths annually in the US. Risk increases with:

• Higher radon concentration levels
• Longer duration of exposure
• Smoking (radon and smoking together multiply cancer risk dramatically)
• Time spent in lower levels of the home where concentrations are highest

Testing Methods

Short-Term Testing (48-96 hours)

Most common during real estate transactions. A testing device is placed in the lowest livable area of the home for 48-96 hours under closed-building conditions. Results are available quickly for transaction timelines.

Long-Term Testing (90+ days)

Provides a more accurate annual average since radon levels fluctuate with weather, barometric pressure, and season. Recommended for homeowners not under transaction deadlines.

Continuous Radon Monitors

Electronic devices that measure radon levels hourly, providing detailed data and tamper detection. These are the standard for real estate testing. At Closer Look Home Inspectors, we use continuous monitors for the most reliable results.

Understanding Results

• Below 2.0 pCi/L: Low risk, no action typically needed
• 2.0-3.9 pCi/L: Moderate risk, consider mitigation, especially with long-term occupancy
• 4.0 pCi/L and above: EPA recommends mitigation. This is the action level for real estate transactions
• Above 8.0 pCi/L: High levels requiring prompt mitigation

We routinely see levels ranging from 2.0 to 15.0+ pCi/L in Mankato homes. Some homes test well above 20.0 pCi/L.

Radon Mitigation

If levels exceed 4.0 pCi/L, mitigation is recommended. The most common system is sub-slab depressurization:

• A pipe is installed through the basement floor into the gravel layer beneath
• A fan creates suction, drawing radon from under the slab before it enters the home
• The gas is vented above the roofline where it dissipates harmlessly
• Systems reduce radon levels by 80-99% in most homes
• Installation cost: $800-$1,500 in the Mankato area
• Annual operating cost: $50-$150 in electricity

Radon and Real Estate

Radon testing is a standard part of home transactions in Mankato. Key points:

• Sellers must disclose known radon test results in Minnesota
• Most buyers request radon testing as part of their home inspection
• Elevated results commonly lead to mitigation negotiations
• Having a mitigation system already installed removes this negotiation point for sellers

Schedule radon testing with your home inspection from Closer Look Home Inspectors.

Contact Closer Look Home Inspectors at (507) 721-3820 or get your instant quote below.