A citizen map of radon

A citizen map of radon

Every point on this map is a radon measurement taken in someone's home, in Canada, and submitted anonymously — before or after mitigation. These citizen measurements are not certified: they outline at-risk sectors without guaranteeing any single building. The absence of data does not mean the absence of risk.

Radon is a naturally occurring radioactive gas that seeps into buildings from the ground. It's invisible and odorless. Prolonged exposure increases the risk of lung cancer.

Bq/m³ = becquerels per cubic meter. This is the unit used to measure radon concentration in the air. The higher the number, the higher the concentration.

What should you do? — Under 100 Bq/m³: acceptable. 100 to 200: worth monitoring, consider a long-term test (≥ 91 days). Above 200: Health Canada recommends mitigation.

Read the markers

Outer ring: thick dark = high · thin grey = to watch · none = low

Dashed outline = test under 91 days (indicative, less reliable)

Measured more than 200 Bq/m³?

Radon levels vary by season. Tests under 91 days are labeled “indicative” and are less reliable.