St John's Radon Map: Every Home Health Canada Tested, and What It Read

156 homes across St John's were long-term tested for radon in the two federal surveys. Every one is a dot on this map, coloured by what it read, with the number of tested homes printed beside every district figure.

The Map

Every dot is one tested house. Zoom in for street names. Shaded districts had no home tested in either survey. This page covers postal districts A1. The whole province is on the Newfoundland and Labrador map.

under 100100 to 147148 to 199200 and aboveno homes tested

156 measurements shown. Dot positions inside a district are illustrative, not addresses. The survey records which district a home was in, never where it stood. Tap any dot for its reading, or any district for its count and median. Rural districts here cover thousands of square kilometres, so a dot in one says very little about any particular corner of it.

Built from Health Canada's published measurements under the Open Government Licence. We do not sell radon testing or mitigation.

What the Numbers Say

6%
of tested St John's homes at or above Canada's 200 Bq/m³ action level
73
median reading, Bq/m³
447
highest single reading, in A1X

St John's sits 28th of the 33 places mapped with a hundred or more tested homes, at 6.4% at or above the action level, between Halifax at 35.2% and Toronto and the GTA at 2.2%. All on the same two surveys and the same method. The spread between places is real, and the spread between houses on one street is bigger still.

The Number Changes Depending on Whose Limit You Use

Canada acts at 200 Bq/m³. The United States EPA acts at about 148. The World Health Organization sets a reference level of 100. Applied to the same 156 homes:

6%
at or above Canada's 200
15%
at or above the US EPA's 148
33%
at or above the WHO's 100

Same houses, same measurements. Why the three numbers differ, and which one to use.

By Postal District, with the Sample Sizes Shown

Read the count column before the median column. A district resting on four houses is a hint, not a verdict, and those rows are greyed. The land area column matters too: a district covering ten thousand square kilometres is an average across a region, not a neighbourhood.
DistrictLand km²Homes testedMedianHighestAt or over 200
A1H154111022101
A1S1583991560
A1N1621962521
A1L304791080
A1A4223742011
A1B5216743301
A1Y1314743231
A1E1425672513
A1W23255780
A1G1113531960
A1K86245690
A1C4842780
A1X363304471
A1V10521262701

7 districts have ten or more tested homes, which is where these figures start to mean something. The districts with no measurement at all are A1M.

What Actually Settles It

Nothing on this page describes your house. Radon varies enormously between homes on the same street, because it depends on how each building sits on and draws air from the ground beneath it. The highest reading here is 447 Bq/m³ and it sits in a district whose median is far below it. A long-term test in your own home is the only measurement that tells you anything about your home.

Also: every C-NRPP certified radon company here, the other city and province maps, and what radon actually is.

Sources and method. Radon measurements: Health Canada, Radon and Thoron Data From Canadian Homes pooled with the Cross-Canada Survey of Radon Concentrations in Homes 2009-2011, both under the Open Government Licence – Canada. Boundaries: Statistics Canada 2021 cartographic forward sortation area file, same licence. Percentages are calculated from the individual measurements shown, not quoted from a summary. Land areas are from the Statistics Canada boundary file.