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The radon guides.

Ten primary-source-cited guides covering the EPA's zone map, testing, mitigation systems, real-estate disclosure, and the actual epidemiology behind the EPA's risk numbers. Every claim sourced to a federal publication, peer-reviewed paper, or standards document.

Last reviewed 30 June 2026 · 10 guides
No. 01 · Foundations

EPA Radon Zones explained: what each zone means for your home

Zone 1, 2, and 3 defined directly from EPA-402-R-93-071 — what the classification predicts about indoor levels, what it doesn't, and when state data overrides the federal map.

10 min read
No. 02 · Testing

Short-term vs long-term radon testing — which to use when

2–7 day kits vs. 90+ day kits. Trade-offs, the EPA's recommended protocol, when to escalate, and how to read the result against the action level.

9 min read
No. 03 · Mitigation

Sub-slab depressurization: how mitigation systems actually work

The dominant residential mitigation technique, pulled straight from EPA-402-K-10-005 and ANSI/AARST SGM-SF-2017 — fan sizing, piping, exhaust placement, monitoring.

12 min read
No. 04 · Geography

The 10 highest-radon US counties (and what they have in common)

The counties with the highest published indoor radon averages, the geology that drives them, and what residents should do differently.

11 min read
No. 05 · Water

Radon in well water: how it differs from soil-gas radon

The separate exposure pathway through private wells in granitic terrain — how to test, what 300 vs. 4,000 pCi/L means, and what an aeration unit costs.

10 min read
No. 06 · Real estate

Selling a home with high radon: disclosure, mitigation, negotiation

EPA-402-K-13-002 in plain English: what disclosure looks like, who pays for mitigation, how to time the work, and how to price the negotiation.

12 min read
No. 07 · Risk

Radon and lung cancer: what the EPA risk numbers actually say

Table A-1 of EPA-402-R-03-003 decoded — lifetime deaths per 1,000 by exposure level, the BEIR VI dose-response, and the Iowa case-control evidence.

12 min read
No. 08 · Testing

DIY radon testing: the right kit, the right placement, the right time

How to test correctly: kit type, placement, closed-house conditions, season, depth in the home, and how to interpret the lab result.

11 min read
No. 09 · Multi-family

Radon in apartments and condos: above-grade unit risk

How the soil-gas pathway changes with floor level, ANSI/AARST MS-PMD-2014 measurement protocol, and what a tenant or HOA can actually do.

10 min read
No. 10 · Retesting

Radon after a basement remodel — why re-testing matters

Why structural changes can void prior test results, the EPA's retest cadence, and the specific scenarios that warrant a fresh measurement.

9 min read

Skip the reading — get the county-specific dossier

The guides are free. The 6-page PDF turns it all into one printable page for your county.

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