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

Indoor Air Quality Assessment for Mankato Area Homes

By Closer Look Home Inspectors | Updated December 2025 | (507) 721-3820

Americans spend approximately 90 percent of their time indoors, and indoor air can be 2 to 5 times more polluted than outdoor air according to the EPA. In Mankato, where homes are sealed tightly against extreme temperatures for much of the year, indoor air quality deserves serious attention. Multiple pollutant sources combine to create air quality concerns that affect health, comfort, and long-term wellbeing.

Common Indoor Air Pollutants in Mankato Homes

Radon

The most significant indoor air quality threat in southern Minnesota. Radon is a radioactive gas that seeps into homes from the soil and is the second leading cause of lung cancer after smoking. Blue Earth County is in EPA Radon Zone 1, and approximately 40 to 50 percent of homes test above the EPA action level of 4.0 pCi/L. Visit our radon testing page for detailed information about testing and mitigation.

Mold Spores

Minnesota's climate creates ideal conditions for mold growth: high moisture from spring snowmelt, humid summers, and condensation in tightly sealed winter homes. Mold produces spores that become airborne and can trigger allergies, asthma, and respiratory irritation. Common mold locations include basements, crawl spaces, bathrooms, and behind walls where moisture accumulates. Our mold inspection service identifies mold growth and the moisture conditions enabling it.

Combustion Byproducts

Carbon monoxide, nitrogen dioxide, and particulate matter from furnaces, water heaters, gas ranges, fireplaces, and wood stoves. In tightly sealed Minnesota homes, inadequate combustion air supply can cause these byproducts to accumulate. See our carbon monoxide safety guide for detailed information.

Volatile Organic Compounds (VOCs)

Off-gassing from paint, adhesives, flooring, furniture, cleaning products, and personal care products. VOC concentrations are typically higher in newly built or recently renovated homes and in homes with limited ventilation. Common symptoms of VOC exposure include headaches, eye irritation, and respiratory discomfort.

Dust and Allergens

Dust mites, pet dander, pollen, and other biological allergens accumulate in homes, particularly in carpeting, upholstery, and ductwork. In Minnesota homes where windows stay closed for months at a time, these allergens concentrate in the indoor environment.

Factors That Affect Indoor Air Quality

Ventilation

Adequate ventilation dilutes indoor pollutants with outdoor air. Many older Mankato homes rely entirely on natural air infiltration through gaps and cracks for ventilation, which provides unpredictable and often inadequate air exchange. Newer, tightly sealed homes may have mechanical ventilation systems, but these must be properly maintained and operated.

Moisture Management

Excess moisture promotes mold growth, dust mite proliferation, and material deterioration. Indoor humidity should be maintained between 30 and 50 percent. In winter, Mankato homes often have very low humidity unless a humidifier is used. In summer, basement and crawl space humidity can exceed 70 percent without dehumidification.

HVAC System Condition

Your heating and cooling system circulates air throughout the home, and its condition directly affects air quality. Dirty ductwork, contaminated filters, and poorly maintained equipment can distribute pollutants rather than remove them. Regular filter changes, duct cleaning when indicated, and system maintenance all support better air quality.

Testing Options

• Radon testing: Professional continuous radon monitors provide the most accurate results. Cost: $125 to $175 as part of a home inspection.
• Mold testing: Air sampling identifies mold spore types and concentrations. Surface sampling confirms visible growth. Cost: $200 to $500 depending on number of samples.
• CO testing: Professional combustion analysis tests CO levels at appliances and in ambient air. Included in our home inspection.
• VOC testing: Specialized laboratory testing for specific volatile organic compounds. Cost: $200 to $400 per sample.
• Humidity monitoring: Inexpensive digital hygrometers ($15 to $30) let you monitor indoor humidity levels in real time.

Improving Indoor Air Quality

• Test for and mitigate radon, the most significant indoor air health risk in our area
• Address moisture problems including basement water intrusion, crawl space humidity, and bathroom ventilation
• Maintain your HVAC system with regular filter changes and professional service
• Ensure adequate ventilation, especially in tightly sealed homes
• Use exhaust fans when cooking and bathing
• Reduce VOC sources by choosing low-VOC products for paint, cleaning, and personal care
• Control dust with regular cleaning, HEPA vacuum filtration, and high-quality furnace filters

Concerned about air quality in your Mankato home? Call Closer Look Home Inspectors at (507) 721-3820 for professional evaluation including radon testing and mold assessment.