Quebec Radon Map: Every Home Health Canada Tested, and What It Read

1,685 homes across Quebec 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.

under 100100 to 147148 to 199200 and aboveno homes tested

1,685 measurements shown, and 64 more with no district recorded that cannot be placed. 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

14%

of tested Quebec homes at or above Canada's 200 Bq/m³ action level

median reading, Bq/m³

2,923

highest single reading, in G4X

Quebec sits 19th of the 33 places mapped with a hundred or more tested homes, at 13.6% 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 1,685 homes:

14%

at or above Canada's 200

19%

at or above the US EPA's 148

30%

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.

District	Land km²	Homes tested	Median	Highest	At or over 200
J1L	26	14	251	1679	7
J1J	8	11	199	858	5
G0E	1,463	10	145	271	4
G4X	2,867	30	134	2923	9
G0C	8,551	60	126	911	23
G4V	4,545	17	116	505	4
H7L	16	10	109	194	0
J1E	18	10	103	482	2
J1G	12	10	101	1049	4
J0X	22,196	15	99	313	1
G7N	1,934	10	88	294	2
G0J	11,516	34	81	661	9
J0L	1,274	10	75	160	0
G4R	26,779	20	74	234	2
G7J	16	10	74	369	1
G0N	1,560	11	73	321	1
J0V	2,378	12	71	262	2
J1N	80	18	68	857	2
J1R	73	12	67	951	1
G0M	3,127	21	66	412	3
J1H	24	11	66	219	1
G4W	195	12	64	369	2
G0R	7,117	44	63	548	8
G0T	2,298	28	63	1331	4
J1K	8	11	54	124	0
G8T	22	13	53	95	0
G8Y	23	16	52	67	0
G7S	36	12	48	704	1
G7X	278	16	44	214	1
G0A	11,122	55	42	2013	8
J0B	5,104	17	42	412	3
G0L	7,984	51	41	481	8
G8W	57	12	41	66	0
J0Z	26,583	18	41	212	1
G5A	458	13	40	190	0
G7H	130	15	39	268	2
G0W	23,303	46	38	492	3
G0S	3,444	24	35	472	3
G8Z	8	13	35	70	0
G9B	83	14	35	92	0
G8P	695	97	32	410	10
G0G	127,524	18	29	126	0
J0K	12,791	26	28	223	1
G4T	187	24	27	331	1
G5L	62	13	25	139	0
J0Y	758,981	27	25	529	2

46 districts have ten or more tested homes, which is where these figures start to mean something. The table shows those; 179 districts with thinner samples are on the map but not listed here. 189 districts have no measurement at all and are shaded on the map.

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 2,923 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 (six Quebec metros) 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.