Spring Radon Testing: Why Now Is the Best Time

What is radon and why it matters

Radon is a colorless, odorless radioactive gas that seeps into homes from naturally occurring uranium in soil and rock. It is the second leading cause of lung cancer in the United States after smoking, responsible for an estimated 21,000 deaths per year. The EPA action level is 4 pCi/L (picocuries per liter) — roughly 1 in 15 US homes tests above this threshold. Because radon is invisible and undetectable without testing, many homeowners live with dangerous levels for years without knowing.

Why spring is the best time to test

• Post-winter baseline — Homes are sealed tightly all winter, allowing radon to accumulate. A spring test captures peak indoor levels before you start opening windows regularly.
• Ground thaw — As frozen ground thaws, soil gas pathways open up and radon migration increases. Spring readings are typically 20–40% higher than summer readings.
• Mitigation scheduling — If levels are high, you can schedule mitigation installation during spring or early summer when contractors have more availability and before the next heating season seals the house again.
• Real estate prep — If you plan to sell, having a recent radon test (and mitigation if needed) removes a common buyer objection.

How to test your home

• Short-term test (2–7 days) — Charcoal canisters or continuous radon monitors placed in the lowest livable area. Cost: $15–$30 for a DIY kit; $150–$250 for a professional test.
• Long-term test (90+ days) — Alpha-track detectors provide a more accurate annual average. Recommended if short-term results are borderline (2–4 pCi/L).
• Place the test device in the lowest level of the home that is regularly occupied — typically the basement or ground floor.
• Keep windows and doors closed as much as possible during the test period (normal entry/exit is fine).
• Do not place the detector in a kitchen, bathroom, or near drafts — these locations give unreliable readings.

Understanding results and next steps

• Below 2 pCi/L — Low risk. Retest every 2–5 years or after major renovations that change the foundation.
• 2–4 pCi/L — Consider a long-term follow-up test. Mitigation is recommended if the long-term average stays above 4.
• Above 4 pCi/L — The EPA recommends mitigation. A sub-slab depressurization system is the most common fix: a pipe and fan pull radon from beneath the foundation and vent it above the roofline.

Mitigation costs and what to expect

Professional radon mitigation typically costs $800–$2,500 depending on home size, foundation type, and system complexity. Most installations take 4–8 hours. A properly installed system reduces radon levels by 80–99% and runs continuously with minimal electricity cost ($50–$75/year). The system includes a manometer gauge so you can visually confirm it is operating. After installation, retest in 24–48 hours to verify levels have dropped below 4 pCi/L.