Alberta · rules and data checked October 8, 2026

Home health check for Lethbridge

In Health Canada's 2012 survey, 9.0% of 111 homes tested in the Chinook Regional Health Authority region were above the 200 Bq/m³ radon guideline; the 2024 Cross-Canada survey found 16.8% (1 in 6) of houses at or above 200 Bq/m³ for Lethbridge, AB. Lethbridge's January averages −6.0 °C (ECCC), with about 63 nights a year below −10 °C, when CMHC advises keeping indoor humidity near 30% to stop window condensation. Alberta does not require carbon monoxide alarms in existing houses.

Radon, 2012 survey

9.0%

above 200 Bq/m³ (111 homes)

Radon, 2024 survey

16.8%

Lethbridge, AB

January average

−6.0 °C

63 nights a year below −10 °C

Private wells

Rare

in Lethbridge

Home health check for Lethbridge

Four quick checks, set up with Lethbridge's winter temperatures and Alberta's alarm rules. Change any value; nothing you enter leaves your browser.

Radon test result

Pre-filled with the 2024 Cross-Canada survey's average (geometric mean) for Lethbridge, AB. Replace it with your own result from a test of at least 3 months.

111Bq/m³ (3.0 pCi/L)

Scale to 800 Bq/m³. 1 pCi/L = 37 Bq/m³.

Below the guideline of 200 Bq/m³. No action is required. Health Canada still advises keeping radon as low as reasonably achievable, and retesting after major renovations or changes to the basement.

Health Canada's lifetime lung cancer risk: for a never-smoker about 1% at low radon, 2% after lifetime exposure at 200 Bq/m³ and 5% at 800; for a smoker 12%, 17% and 30%. Only a test of 3 months or longer gives an annual average; short tests can mislead.

Winter humidity and window condensation
°C
%
Outdoor temperature

January average: ECCC 1981–2010 normals. Cold snap: NRCan's HOT2000 winter design temperature for Lethbridge.

55%highest humidity before the glass fogs at −6.0 °C

Double glazing, clear (1970s–1990s) (U 2.86): condensation starts at about −20.1 °C outside with 40% humidity inside.

The centre of the glass stays dry at −6.0 °C. It is about 11.7 °C, above the 6.9 °C dew point. The bottom edge and frame run colder, so condensation can start there first.

Health Canada and CMHC: keep indoor humidity between 30% and 50%. Below −10 °C outside, CMHC advises about 30%; Lethbridge averages 63 nights a year that cold.

Smoke and carbon monoxide alarms

A sleeping area is a group of bedrooms off one hallway.

Smoke alarms required by law
1
Smoke alarms for full coverage (new-home standard)
6
CO alarms recommended
2

Not required by Alberta law in an existing house, but strongly recommended.

“Full coverage” follows the National Building Code for new homes: one on every storey including the basement, one in each bedroom and one outside each sleeping area, interconnected. CO: NRCan advises one near the furnace or other fuel-burning appliance and one in each bedroom area.

Mould: clean it yourself or call a pro?

Example values shown. 1 m² is about 10.8 sq ft.

Small: you can clean it yourself if you are healthy.

Up to three patches, each under 1 m²: clean with water and unscented dish detergent, wearing safety glasses, an N95 mask and rubber gloves (CMHC). People at risk from mould should not clean it.

Fix the moisture source first. Testing for mould types is usually unnecessary (Health Canada). You entered 2 patches, the largest about 0.5 m².

Lethbridge at a glance

Radon surveys covering Lethbridge
SurveyResult
Health Canada, 2012Chinook Regional Health Authority, 111 homes, long-term tests9.0% above 200 Bq/m³; 0.9% above 600
Cross-Canada survey, 2024Lethbridge, AB (Lethbridge CMA)16.8% (1 in 6) of houses at or above 200 Bq/m³; unweighted geometric mean 110.7 Bq/m³ (report: insufficient information to apply weighting); approx. 300-399 properties with data.

The 2024 survey pools long-term tests that households volunteered, so it is not a random sample, and more tests were in basements than in 2012. Health Canada's guideline: fix a home above 200 Bq/m³ within a year. Test kits cost about $30–$80 including the lab; mitigation about $2,000–$3,000.

Highest indoor humidity before windows fog (21 °C inside)
WindowAt −6.0 °CAt −26.1 °C
Single glazing with a storm windowU 2.954%34%
Double glazing, clear (1970s–1990s)U 2.8655%34%
Double glazing, low-e and argon (2000s)U 1.869%52%
ENERGY STAR (U 1.22 or better)U 1.2278%64%
Triple glazingU 1.475%60%

Centre of the glass, from the National Building Code's indoor air film and the Magnus dew point formula. January average from ECCC normals; the cold-snap column is NRCan's winter design temperature. Window edges fog sooner, so follow CMHC: about 30% humidity below −10 °C, which Lethbridge sees on about 63 nights a year.

Smoke alarms in Alberta

National Fire Code – 2023 Alberta Edition, Div. B 2.1.3.3: same text as the NFC 2020 (alarm in each dwelling unit between sleeping areas and the rest of the unit; battery-operated alarms permitted, see also Div. C 2.1.1.1(4)).

Existing homes must have them: Yes · Every storey: Not confirmed · In each bedroom: No · Interconnected: No

Law: National Fire Code – 2023 Alberta Edition, Div. B 2.1.3.3

Official source ↗

Carbon monoxide alarms in Alberta

Alberta's building code requires certified CO alarms in every new building that contains a residential occupancy and a fuel-burning appliance and/or an attached storage garage. For existing homes, the province only says CO alarms are 'highly recommended'. The National Fire Code – 2023 Alberta Edition (2nd printing effective 2026-08-17 per alberta.ca) requires only that CO alarms be inspected, tested and maintained per the manufacturer's instructions (Div. B Section 6.7). It adds no requirement to install them in existing homes.

Official source ↗

Well water in Lethbridge

Lethbridge homes are served by the City's municipal water system, so private wells are rare.

  • Bacteria: 2 times a year (Free (Alberta Health Services))
  • Chemistry: Chemicals and trace metals every 3 years (Free (AHS))

Alberta source 1 ↗

Radon help in Alberta

New homes: Yes. The National Building Code - 2023 Alberta Edition (in force May 1, 2024) Division B Subsection 9.13.4 (Soil Gas Control) requires an air barrier against soil gas and, for dwelling units, a rough-in for a radon extraction system under Article 9.13.4.3, "Providing for the Rough-in for a Subfloor Depressurization System".

Test kits: No provincial free-kit program found. Alberta Lung supports library radon-monitor lending, e.g. Edmonton Public Library, Red Deer Public Library, Parkland Regional Library, Marigold Library System and Strathmore Municipal Library (free with a library card). Long-term kits must be bought.

Other help: Lungs Matter mitigation aid (up to $1,500) is available to eligible households (Alberta income cap $112,700).

Find a C-NRPP certified measurement or mitigation professional at c-nrpp.ca. Data checked October 8, 2026.

Common questions in Lethbridge

How common is radon in Lethbridge?

Health Canada's 2012 survey found 9.0% of 111 homes tested in the Chinook Regional Health Authority region at or above 200 Bq/m³. The 2024 Cross-Canada survey, which pools tests that households volunteered, reports 16.8% (1 in 6) of houses at or above 200 Bq/m³ for Lethbridge, AB. Neighbouring houses can differ a lot, so the only way to know is a long-term test of at least 3 months, ideally in the heating season.

What indoor humidity should I keep in winter in Lethbridge?

Health Canada and CMHC advise 30% to 50%, and CMHC says to keep it at about 30% when it is below −10 °C outside (as low as 25% in extreme cold). Lethbridge averages 63 nights a year below −10 °C. At the January average of −6.0 °C, clear double-glazed windows start to fog at about 55% humidity at the centre of the glass, and at about 34% in a cold snap of −26.1 °C; the edges fog sooner.

How many smoke alarms does a house need in Alberta?

National Fire Code – 2023 Alberta Edition, Div. B 2.1.3.3: same text as the NFC 2020 (alarm in each dwelling unit between sleeping areas and the rest of the unit; battery-operated alarms permitted, see also Div. C 2.1.1.1(4)). New homes built to the National Building Code need hardwired, interconnected alarms on every storey and in every bedroom, which is the standard we recommend for full coverage.

Are carbon monoxide alarms required in Alberta?

Alberta's building code requires certified CO alarms in every new building that contains a residential occupancy and a fuel-burning appliance and/or an attached storage garage. For existing homes, the province only says CO alarms are 'highly recommended'. The National Fire Code – 2023 Alberta Edition (2nd printing effective 2026-08-17 per alberta.ca) requires only that CO alarms be inspected, tested and maintained per the manufacturer's instructions (Div. B Section 6.7). It adds no requirement to install them in existing homes.

How often should I test my well water in Alberta?

Bacteria: 2 times a year. Chemistry: Chemicals and trace metals every 3 years. Bacteria test cost: Free (Alberta Health Services). Lethbridge homes are served by the City's municipal water system, so private wells are rare.

How we calculate this

Radon

1 pCi/L = 37 Bq/m³ (Health Canada). The Canadian guideline is 200 Bq/m³; above it Health Canada recommends fixing your home within 1 year, sooner the higher the level. Only a long-term test (at least 3 months, ideally in the heating season) tells you your annual average.

Window condensation

glass temperature = indoor − U × (indoor − outdoor) ÷ 8.33

8.33 W/m²·°C is the indoor air film from the National Building Code (RSI 0.12). The dew point comes from the Magnus formula the US National Weather Service publishes; condensation forms when the glass is colder than the dew point. These are centre-of-glass figures: the bottom edge and metal frames run colder, which is why we show CMHC's simpler rule beside them (30% indoor humidity when it is below −10 °C outside, as low as 25% in extreme cold).

Smoke and CO alarms

“Required by law” applies your province's fire code to the layout you enter. “Recommended” is the new-home standard in the National Building Code (an alarm on every storey, in every bedroom and outside sleeping areas) and NRCan's CO advice (one near the furnace or other fuel-burning appliance and one in each bedroom area). Municipal by-laws can add to provincial rules.

Well water and mould

Testing frequencies and lab fees are the ones your province publishes. Mould size categories are Health Canada's and CMHC's: up to three patches each under 1 m² can be cleaned by a healthy homeowner; more than 3 m² needs a professional.

More for Lethbridge

Heating and hot water costs in LethbridgeWhat heating, hot water and air conditioning cost at your local prices, and what each heating system would cost instead.Upgrade payback in LethbridgeSavings, rebates and payback for attic, wall and basement insulation, windows, air sealing and thermostat setbacks.Appliance running costs in LethbridgeWhat your fridge, dryer, freezer and other appliances cost to run at your local electricity price, and what a newer model saves.
Build your upgrade plan → All home services in Lethbridge Radon testing in LethbridgeCarbon monoxide testing in LethbridgeWell water testing in LethbridgeMould testing in LethbridgeVentilation assessments in Lethbridge Alberta rebates and programs

Sources

Prices and programs checked October 8, 2026. Climate: NRCan HOT2000 (Lethbridge) for heating and ECCC 1981–2010 normals (Lethbridge A) for cooling and temperatures.

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