Radon in Hamilton
Hamilton is one of the few places in our service area with published local data.
Hamilton radon guide
Radon in Hamilton
Radon testing and mitigation in Hamilton
Lower City on the old lake plain, the Mountain on the Escarpment, and growing suburbs from Ancaster to Stoney Creek.
Radon in Hamilton
Hamilton is one of the few places in our service area with a published local radon survey. In a public health survey of 294 Hamilton homes, 42 (about 14%) came in above Health Canada’s guideline, roughly three times the provincial average reported at the time. That doesn’t mean your home is high. It does mean no part of the city should assume it’s low.
What’s under the ground
Hamilton is split by the Niagara Escarpment. The Lower City sits on the Iroquois Plain, made of beach sands, gravels and lake clays from glacial Lake Iroquois. Above it, the Mountain and Ancaster sit on dolostone cap rock with thin soils, where joints and fractures in the rock can carry soil gas.
The homes
The housing stock runs from 1900s brick homes in Kirkendall, Durand and Crown Point to post-war bungalows on the Mountain and new construction in Waterdown, Binbrook and Stoney Creek. Older lower-city homes often have stone foundations. Newer suburban homes are larger and more airtight.
Public health: Hamilton Public Health Services.
What the data says
14%
Of 294 Hamilton homes in a public health survey were above the 200 Bq/m³ guideline (42 homes), as reported by Global News.Source: Global News — Hamilton public health survey of 294 homes
1 in 8
Ontario homes at or above Health Canada’s 200 Bq/m³ guideline in the 2024 Cross-Canada Survey, more than double the share found a decade earlier.Source: Cross-Canada Survey of Radon Exposure in the Residential Buildings of Urban and Rural Communities (2024)
~100
Roughly how many homes per health region the first national survey (2009–2011) could test. Too few to clear any neighbourhood, which is why public maps can’t tell you about your house.Source: Health Canada — Cross-Canada Survey of Radon Concentrations in Homes, Final Report (2012)
Local factors
Why Hamilton homes should test
Shallow or fractured bedrock
Where rock sits close to the surface, as on the Niagara Escarpment or the limestone plains near Lake Erie, joints and fractures can act as pipelines that carry soil gas toward foundations.
Sandy or gravelly soils
Sand and gravel let soil gas move freely and over longer distances. More of the radon formed in the ground can reach the air around your foundation instead of decaying in place.
Century homes
Fieldstone, rubble and early concrete foundations, earth-floor cellars and open sumps give radon many ways in. Older doesn’t mean safer: these homes still need a test.
New, airtight construction
Canadian research shows newer homes have tended to test higher than older ones. Bigger, taller and tighter homes create a stronger stack effect that draws soil gas in through the slab.
Lived-in basements
Radon is usually highest on the lowest floor. Basement bedrooms, home offices and rental suites mean people spend hours a day where exposure is greatest.
Questions
Radon in Hamilton: common questions
How many Hamilton homes have high radon?
In a Hamilton public health survey of 294 homes, 42 (about 14%) were above the 200 Bq/m³ guideline. A single survey can’t predict any one house, but it shows high radon is not rare in Hamilton.
Is radon worse on the Mountain or in the Lower City?
There’s no published split, and either can be high. The Mountain sits on fractured dolostone with thin soils, while the Lower City sits on sands, gravels and clays. Both give soil gas a way in. House construction and how the home is heated matter as much as the ground.
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C-NRPP certified testing and mitigation across Hamilton, Ancaster.