The useful question isn’t whether a kit is accurate — it’s whether it measures the thing you’re worried about, in the place that thing shows up. Free path first, then the paid kit, then what a result should and shouldn’t tell you.
Not sure where to start?
Your address decides which test comes first
Radon, water contaminants, and lead paint cluster by geography, water source, and build year.
Charcoal canister, alpha track, and electret devices are EPA's own recommended short-term test types; the analyte (radon gas) is unambiguous, the test is inexpensive, and a result at or above the 4 pCi/L action level maps directly to an established fix (sub-slab depressurization) — validated and actionable, the same tier as blood lead testing.
Free path first
Many state radon programs and local health departments distribute free or discounted short-term test kits — EPA directs homeowners to their state radon office to check availability before buying one.
Genuinely useful as a trend tool for spotting VOC/PM2.5 spikes after new furniture, paint, flooring, or heavy candle/air-freshener use, and for checking whether ventilation habits are working. Not tier 1 because there is no single validated action threshold to score a reading against — EPA has no federally enforceable indoor VOC standard and states it has no authority to regulate household products or indoor air quality generally. EPA's own guidance on these devices also flags real accuracy/precision limitations, sensitivity to placement/temperature/humidity, degrading reliability over device lifespan, and explicitly notes their alerts are not designed to warn of danger the way a CO or smoke alarm is. Not tier 3 because the readings are not meaningless — they're a legitimate relative signal, just not a pass/fail safety test.
Free path first
Source control (choosing lower-VOC products, airing out new furniture/flooring before use) and increased ventilation (open windows, run exhaust fans) are EPA's first-line recommendations for reducing indoor VOCs, ahead of any device — both cost nothing.
Tier 1Validated and actionable — a recognized method with a published threshold to act on.
Tier 2Defensible with conditions — useful if you know exactly what it does and doesn't detect.
Tier 3Not recommended — never publishes as a recommendation on this site.
The free alternative is always named before any paid option — naming the free path is what makes a paid recommendation credible.
Health screening
Coming soon
Everything above tests a house. The other half of the picture is whether the people in it are current on the screenings their doctor would actually recommend — which is a different question, answered by different tools, and one we’d rather build properly than quickly. It’s coming, because health is most of what safety means.
