Indoor Air Quality: Why Your Home Can Be 5x Worse Than Outside

Modern homes are built tight. That's great for energy bills, but it means whatever you bring inside — cleaning products, off-gassing furniture, candles, cooking fumes — gets concentrated rather than diluted. The EPA reports that indoor air can hold pollutants at levels two to five times higher than outdoor air, sometimes much more.

The biggest indoor air pollutants

• VOCs from paint, new furniture, carpet, and cleaning products

• Combustion byproducts from gas stoves, fireplaces, and water heaters

• Mold spores from damp basements, bathrooms, and HVAC systems

• Particulate matter from cooking, candles, and outdoor air infiltration

• Radon — naturally occurring radioactive gas from soil

Symptoms that point to indoor air

If headaches, congestion, or itchy eyes consistently improve when you leave the house and return when you come home, that's a strong signal. Same with kids whose asthma flares only at certain times of year — often when the heat or AC kicks on and stirs up the HVAC system.

Quick wins before you test

1. Run kitchen exhaust fans every time you cook on gas

2. Open windows for 10 minutes a day even in winter

3. Vacuum with a HEPA filter, weekly

4. Avoid scented candles and plug-in air fresheners

When to test

If symptoms persist or you're moving into a new build, an indoor air quality test will measure VOCs, formaldehyde, and particulate levels. Add a separate radon test — it's the only way to know your radon level and it's the second-leading cause of lung cancer in the U.S.