Radon and Indoor Air Quality: What's Actually Worth Testing For

Indoor air quality concerns range from genuinely serious and easy to test for, to marketing-driven concerns with little practical benefit from a home detector. Radon and carbon monoxide sit firmly in the first category.

Radon: test regardless of your area's general risk level

Radon is a naturally occurring radioactive gas that seeps up from soil and rock and can accumulate in enclosed spaces, particularly basements. It's odorless and invisible, and long-term exposure at elevated levels is a well-established lung cancer risk, second only to smoking. Regional radon risk maps are useful for context but not a substitute for testing — levels vary significantly even between neighboring homes depending on foundation type and local geology.

Radon mitigation, if needed

The standard fix is a sub-slab depressurization system: a pipe and fan that draw radon-laden air from beneath the foundation and vent it above the roofline before it enters the living space. This is a licensed-contractor job in most cases — it requires understanding the specific foundation type and often permitting, and a poorly installed system can be ineffective or even depressurize the house in unintended ways.

Carbon monoxide: a life-safety issue, not an air-quality nuance

CO is produced by incomplete combustion in fuel-burning appliances — furnaces, water heaters, gas stoves, fireplaces, and attached garages. Unlike radon, CO exposure can be acutely dangerous within hours, not just over years. Every home with any fuel-burning appliance or an attached garage should have working CO detectors near sleeping areas, tested regularly, with batteries replaced on schedule.

• Install CO detectors outside each sleeping area and on every level of the home.
• Have fuel-burning appliances and chimneys/flues inspected annually by a qualified technician.
• Never run a generator, grill, or any gas engine inside a garage, even with the door open.
• If a CO alarm sounds, get everyone outside into fresh air immediately and call emergency services before troubleshooting the source.

VOCs, particulates, and general 'indoor air quality' monitors

Consumer air quality monitors that track VOCs (volatile organic compounds) and fine particulate matter (PM2.5) can be genuinely useful for tracking trends — for example, confirming that a range hood reduces cooking-related particulates, or that a new piece of furniture is off-gassing noticeably. They're a lower safety priority than radon and CO detection and are more about comfort optimization than acute risk.

Ventilation is the common thread

Whether the concern is radon, VOCs, or general stuffiness, adequate fresh-air exchange dilutes whatever is accumulating indoors. Bathroom and kitchen exhaust fans, an HRV or ERV system in tighter modern homes, and simply opening windows when weather allows all reduce indoor pollutant concentrations broadly, even without addressing a specific source.

A worked example: interpreting a radon test result

A short-term test returning 3.2 pCi/L sits in the 2-4 range where guidance leans toward considering mitigation rather than requiring it outright. A sensible next step is a second short-term test or a 90-day long-term test to see if the reading holds, since radon can swing with weather, season, and even whether windows were open during the test. A result of 4.8 pCi/L, by contrast, is squarely in the range where mitigation is generally recommended without waiting for further confirmation.

1. Buy a short-term radon test kit and place it in the lowest lived-in level, away from drafts, doors, and windows.
2. Leave it undisturbed for the full 2-7 day period specified on the kit.
3. Mail it to the lab as instructed and wait for results.
4. If results fall at or above 4 pCi/L, get a confirming test or move directly to contacting a licensed radon mitigation contractor.
5. Retest roughly every 2 years, and again after any renovation affecting the foundation or HVAC system.

• Common mistake: skipping a radon test because the general regional risk map shows low risk — levels vary house to house regardless of the map.
• Common mistake: testing with windows open or during unusually windy weather, which can skew short-term results lower than typical conditions.
• Common mistake: treating an air purifier as a radon solution, when only sub-slab ventilation actually removes the gas.
• Common mistake: forgetting to retest after a renovation that changes the home's air sealing or HVAC setup, since either can shift radon levels.
• Common mistake: placing CO detectors only in the kitchen instead of also near sleeping areas, where alerting occupants during sleep matters most.