About
Why this site exists
Radon is a naturally occurring radioactive gas that enters buildings through the ground. In Québec, the information available on real concentrations has been limited to geological potential maps and sector-level surveys: no community solution existed where people could deposit and browse actual measurements taken in their own homes. This site fills that gap.
What the map does
Anyone can deposit, anonymously and free of charge, the radon measurement taken at home — before and after mitigation, where applicable. The map aggregates these measurements to reveal areas where reported concentrations are high. Measurements are citizen-reported and not certified: an area showing no data does not mean there is no risk (see the legal notice).
Who is behind this project
This site was created by Jérémie Dufault. LinkedIn It is an independent project, run on a volunteer basis.
Methodology
The measurements shown come exclusively from anonymous citizen submissions. Each contributor deposits their own measured value, before or after mitigation. No account is required, and no identity is collected.
The map aggregates these measurements by sector to reveal local trends. Each point’s published position is jittered. It is deliberately distinct from the measurement’s real position, protecting the contributor’s anonymity.
Tests shorter than 91 days are labeled “indicative” and excluded from sector averages.
Moderation
Every submission is reviewed by the site’s operator before publication. The criteria follow the thresholds already published in the legend: 100 and 200 Bq/m³. An outlier or inconsistent value is examined before display.
The public texts attached to a measurement are reviewed as well. Only approved measurements appear on the map. Processing usually takes a few days, longer in busy periods.
What the data shows
Every figure below covers the whole set of measurements published on the map, as submitted by contributors.
- 65 measurements published, across 34 distinct forward sortation areas.
- 27 of them (42%) are at or above 200 Bq/m³, the level at which Health Canada recommends taking action.
- 12 fall between 100 and 199 Bq/m³, the band worth watching with a long-term test.
- 51 come from a long-term test (≥ 91 days), the measurement that counts.
- 12 were reported after mitigation work.
These are citizen measurements, not certified ones: they outline at-risk areas without guaranteeing anything about a specific building, and an absence of data does not mean an absence of risk. Only a measurement taken in your own home can tell you what your air contains.
Figures computed on 2026-09-24. These aggregate figures are reusable under the CC BY 4.0 licence — see the legal notice.
Support the project
If you find the map useful, you can support its hosting and running costs via Liberapay:
