Canadian Building Codes and Radon: What Ontario Homeowners Need to Know (2026 Guide)

A note before you read. This article is general information about Canadian building codes and radon as of May 2026. It is not legal, professional, or warranty advice, and is not a substitute for advice from a qualified building professional, real estate lawyer, or your provincial / municipal Building Department. Always verify current rules directly with the relevant authority before relying on this article for a specific build, claim, or transaction.

Health Canada estimates that about 1 in 5 Canadian homes has radon levels above the guideline of 200 becquerels per cubic metre — the level at which Health Canada recommends taking corrective action. Radon is the leading cause of lung cancer in non-smokers in Canada, and an estimated 3,200 Canadians die from radon-related lung cancer every year.

Most homeowners assume their new home is protected by the building code. Partly true — the codes have been moving in the right direction for fifteen years. But there's a gap between what the code requires at construction and what your home actually needs to keep radon levels below the Health Canada guideline of 200 Bq/m³. The code prepares your home for mitigation. Only a test tells you whether you need any.

This guide walks through how Canadian building codes deal with radon — federally, provincially, and in Ontario specifically — what the new National Building Code 2025 changes, the layered Hamilton, Guelph, and Kingston municipal programs, and how Ontario's Tarion warranty can cover up to $50,000 of mitigation work for new homes within their 7-year warranty window.

In 60 seconds

• The Canadian building code does not guarantee your home's radon levels are below the Health Canada guideline. It requires construction features that make future mitigation easier and cheaper if a test shows your home needs it.
• The 2024 Ontario Building Code (in force January 1, 2025) requires every new home in Ontario to have a "rough-in" — a capped vent pipe through the slab, plus sealing details. The rough-in is infrastructure, not protection.
• The National Building Code 2025 (released December 22, 2025) upgrades this to a full passive vertical radon stack. Provinces have approximately 18 months to adopt it.
• Older Ontario homes (built before January 1, 2025, outside three small designated areas) generally have no radon construction features at all.
• Ontario's Tarion warranty covers up to $50,000 of radon mitigation if a qualifying test shows levels above 200 Bq/m³ and the home is within its 7-year warranty window.
• The only way to know your actual radon level is to test. Our 91-day kit qualifies for Tarion warranty claims → Order yours $89 all-in →

Table of contents

1. Why this matters: radon in Canadian homes
2. How Canadian building codes work
3. The two federal milestones: NBC 2010 vs NBC 2025
4. Where each province stands today
5. Ontario in detail: the 2024 Ontario Building Code
6. Municipal overlays: Hamilton, Guelph, Kingston, and others
7. The Tarion radon warranty
8. What you can actually do
9. Frequently asked questions
10. Disclaimers
11. Sources

1. Why this matters: radon in Canadian homes

Radon is a naturally occurring radioactive gas produced by the breakdown of uranium in soil and rock. It's colourless, odourless, and tasteless. It seeps into homes through cracks in foundations, gaps around service penetrations, sump pits, and crawl spaces.

Outdoors, radon dilutes to harmless levels. Indoors — especially in basements during the heating season, when homes are sealed against the cold — it can accumulate to concentrations that pose a real health risk over time.

Health Canada's published guideline is 200 becquerels per cubic metre (Bq/m³). Above that level, Health Canada recommends taking corrective action within one year (sooner if levels are much higher).

A few facts worth knowing:

• Radon is the leading cause of lung cancer in Canadian non-smokers and the second leading cause overall after smoking.
• Modern mitigation systems typically reduce radon levels by 80% or more when properly installed (Health Canada cites reductions of more than 80%; CARST cites up to 95%).
• No region of Canada is radon-free. Two homes side by side can have very different radon levels — depending on soil conditions, foundation type, ventilation, and how the home is operated day to day.
• The only way to know your level is to test. Construction-era assumptions ("our area is low risk") aren't reliable.

A note on the number. Health Canada's published language is "exceeds 200 Bq/m³." That means above 200. A result at exactly 200, or below 200, does not exceed the guideline. In whole-number terms, 201 and higher qualifies for the action recommendation. This becomes important when we get to Tarion warranty claims.

2. How Canadian building codes work

Canadian building codes operate in two layers, which trips up a lot of homeowners reading code summaries online.

The federal layer is the National Building Code of Canada, developed by the Canadian Board for Harmonized Construction Codes. The National Building Code is a model — it has no legal force on its own. It's what provinces are working toward.

The provincial and territorial layer is the binding one. Each province and territory adopts the National Model Codes into its own legislation, often with local amendments. What actually applies on a job site depends on the provincial code in force at the time the building permit was issued.

This means when commentators say "the National Building Code now requires X," it does not mean X is required everywhere. It means X is in the model that provinces are working toward — and adoption typically lags federal publication by 1 to 3 years. Some provinces (British Columbia, Quebec) move quickly. Others move slowly.

A third optional layer applies in some Ontario municipalities: municipal radon programs that go beyond the provincial Building Code. Hamilton, Guelph, and Kingston all run such programs (see Section 6).

3. The two federal milestones: National Building Code 2010 vs 2025

Two federal milestones define where Canadian residential radon construction stands today.

The three levels of protection

Most discussion of radon in building codes uses a three-level mental model:

Where each Canadian code sits today:

• Most provincial codes anchor on the 2010 National Building Code and require Level 1 only.
• British Columbia's 2024 code effectively requires Level 2.
• Quebec is moving toward Level 2.
• The 2025 National Building Code moves the federal model from Level 1 to Level 2.
• No Canadian provincial building code currently requires Level 3 (active mitigation) at the time of construction. Some Ontario municipalities (notably Guelph and Hamilton, depending on the building type and option chosen) come closer to Level 3 in their municipal overlays — see Section 6.

4. Where each province stands today

As of May 2026, no province has yet formally adopted the 2025 National Building Code. The table below reflects what is actually in force.

The takeaway: most Canadian provinces sit at Level 1 (rough-in only) today. British Columbia and Quebec are ahead. The 2025 National Building Code will pull everyone toward Level 2 over the next 1 to 3 years.

Always check the specific province where the home was built before relying on any of this for a permit application or a warranty claim.

5. Ontario in detail: the 2024 Ontario Building Code

The 2024 Ontario Building Code came into force on January 1, 2025. After a transition window that closed on March 31, 2025, all permit applications must use the 2024 Ontario Building Code. The radon and soil-gas provisions apply to every new Part 9 residential building — detached houses, semis, row and stacked townhouses, additional dwelling units, and low-rise multi-residential — across the entire province.

What the 2024 Ontario Building Code requires

Section 9.13.4, supported by Supplementary Standard SB-9, sets out the required construction package for every new home:

• A 100 mm vent pipe rough-in through the slab into a centrally located granular layer below, with a removable sealed cap and labelling above the slab.
• A soil gas barrier — typically 6 mil polyethylene — beneath the slab, with overlapping seams.
• Sealed slab perimeter and penetrations, using flexible polyurethane caulking.
• A sealed sump pump cover designed to resist removal by children.
• Continuous air barriers across control joints, junctions, and penetrations to reduce soil gas ingress.

What the 2024 Ontario Building Code does NOT require

This is the part most often misunderstood. The 2024 Ontario Building Code does not require:

• A working passive vertical stack to the roof. (The 2025 National Building Code will eventually push Ontario in this direction.)
• Active sub-slab depressurization (fan-driven mitigation).
• Testing of the completed home.
• Builder-funded test kits or homeowner radon education.
• Mitigation if elevated levels are found post-occupancy. (That falls under Tarion warranty rules, covered below — not the Building Code.)

Older Ontario homes — what was required when

• 2012 Ontario Building Code (in force November 2012 to December 31, 2024): The radon rough-in was required only in three designated areas — Elliot Lake, Faraday Township, and Hyman Township. Everywhere else was exempt.
• Pre-2012: No radon-specific construction requirement in the Ontario Building Code.

Why this matters in resale. Almost all existing Ontario housing stock — including newer suburban builds completed before 2025 — was constructed without a radon rough-in. Retrofitting active mitigation into a finished basement typically costs $2,500 to $4,500, compared to a few hundred dollars to activate a rough-in at construction. This isn't a defect; it reflects what the code required at the time. But for the homeowner, it means testing is even more important.

Bottom line for any Ontario home: the code prepares the house for mitigation if needed. It doesn't tell you whether you need mitigation. Only a long-term radon test in your basement can do that. Our 91-day Tarion-eligible test is $89 all-inclusive → Order

6. Municipal overlays: Hamilton, Guelph, Kingston, and others

Some Ontario municipalities have implemented radon programs that go beyond the provincial Building Code. Three stand out, plus an honourable mention.

Guelph — most rigorous certification framework in Canada

The City of Guelph operates one of the most rigorous municipal radon construction frameworks in Canada. Under the current rules (in force for permit applications filed after December 31, 2024):

• All new ICI (Industrial / Commercial / Institutional) and Part 3 multi-residential buildings must be designed and constructed in accordance with radon mitigation requirements in the Ontario Building Code, with additional Guelph-specific certification.
• All permit applications for new buildings, and for additions exceeding 50 m² in building area, must include a complete copy of the City of Guelph Radon Mitigation Certification Form.
• Before the building permit can be closed, a radon analysis certificate showing the radon concentration does not exceed 200 Bq/m³ must be submitted to the City Inspector (for buildings subject to the program).
• Important note: As part of the changes introduced in the 2024 Ontario Building Code, post-construction radon gas testing is no longer required for new Part 9 residential buildings (single-family houses) under Guelph's program — these are now subject to the 2024 OBC provincial standard. Guelph's program continues to apply primarily to ICI and Part 3 multi-residential buildings, plus all new buildings and additions over 50 m² requiring the certification form.

Source: City of Guelph — Radon Gas Mitigation Program. For a deeper dive into Guelph specifically, see our Radon in Guelph guide.

Hamilton — three-option model with mandatory testing

Hamilton's residential construction requirements give builders a choice between three approaches for new Part 9 residential buildings (in force for new building permits applied for after November 16, 2020):

1. Option 1: Install the Ontario Building Code rough-in plus standard soil gas mitigation measures.
2. Option 2: Install a passive radon venting system.
3. Option 3: Install a full active sub-slab depressurization system.

Depending on the option chosen, mandatory post-construction radon testing applies, with results submitted to the City. All required radon testing must be a long-term test (minimum 91 days) completed during the winter heating season (October to April). If results exceed 200 Bq/m³, the property owner must install an active sub-slab depressurization system. Hamilton operates one of the few mandatory test-and-mitigate cycles for new residential construction in Ontario.

Source: City of Hamilton — Residential Construction Requirements for Radon Gas Mitigation. For a deeper dive into Hamilton specifically, see our Radon in Hamilton guide.

Kingston — municipal compliance + KFL&A Public Health framework

The City of Kingston requires building code compliance for radon mitigation for new low-rise residential construction permits applied for after August 31, 2019. The municipal strategy aligns with Ontario Building Code radon mitigation requirements. Kingston's program operates alongside KFL&A Public Health's community-level testing initiatives — KFL&A offers $20 certified radon test kits to residents and has analyzed over 1,000 home radon tests in the Kingston, Frontenac, and Lennox & Addington area.

Sources: City of Kingston — Radon Gas Mitigation; KFL&A Public Health. For a deeper dive into Kingston specifically, see our Radon in Kingston guide.

Niagara Region

Niagara Region has implemented radon-aware construction inspection protocols that go beyond the baseline Ontario Building Code requirements, with similar features to Hamilton and Kingston in spirit. Always check the specific municipality where the home was built for current local rules.

Other Ontario municipalities

Several additional Ontario municipalities have inspection protocols requiring labelling, sealing verification, and granular fill confirmation prior to slab pour. These don't change the substantive code requirements but tighten enforcement. Always check the specific municipality where the home was built.

7. The Tarion radon warranty

Ontario is one of the only places in Canada whose statutory new-home warranty covers radon — for a province-by-province comparison see our new-home warranty guide. The Tarion warranty has covered radon as an environmentally harmful substance or hazard since March 25, 2013. Coverage runs for 7 years from your possession date.

Coverage limits

What triggers coverage

Three conditions must all be true:

1. The home is within its 7-year warranty window.
2. A qualifying long-term test has been conducted.
3. The test result is above 200 Bq/m³ — the Health Canada guideline.

Testing alone does not trigger coverage. A result at or below the guideline means there's no covered claim. Testing is the gating step; the trigger is the elevated reading.

The test Tarion will accept

Tarion's published guidelines have two requirements that must both be satisfied:

1. The device or the testing professional must be certified through the Canadian National Radon Proficiency Program — Canada's body that certifies radon devices, professionals, and labs.
2. The test must be a long-term test of at least 3 months, conducted in line with Health Canada's measurement guidance, in the basement (not a crawl space).

Our 91-day alpha track test kit qualifies on both fronts. The detector is approved by the Canadian National Radon Proficiency Program. Lab analysis is performed by Lex Scientific in Guelph, Ontario — a Canadian lab certified by the Canadian National Radon Proficiency Program and accredited to ISO/IEC 17025. You receive a written lab report, emailed to you, which is the document you attach to your builder notification and your Tarion warranty claim. $89 all-inclusive — both-way shipping, lab analysis, and report all included. Order your test kit →

How the claim process works (in brief)

1. Notify your builder in writing, with a copy of your lab report attached.
2. Register at myhome.tarion.com and submit the appropriate warranty form for your warranty year.
3. The submission triggers a 120-day builder repair period, during which mitigation is arranged.
4. If unresolved, request a Tarion conciliation.
5. After mitigation, verify with a post-mitigation test that levels are below 200 Bq/m³.

For the full filing process, common pitfalls, and the seven most-asked Tarion questions, see our full Tarion radon warranty claim guide.

8. What you can actually do

The code prepares your home. The warranty protects your wallet if a test comes back high. But neither one tells you whether your home actually has elevated radon. The only way to know is to test.

If your home is in any of these categories, testing is especially worthwhile:

• A new Ontario home under the 2024 Ontario Building Code (most permits issued January 1, 2025 onward). The rough-in is in place. Test once you've lived in the home for at least three months. If results exceed 200 Bq/m³, file a Tarion warranty claim.
• A resale Ontario home that's less than 7 years old. The Tarion warranty travels with the home. Confirm the transfer with Tarion, then test.
• Any Ontario home built before 2012, or built between 2012 and 2024 outside the three former designated areas. There's likely no radon rough-in. Test now — and if results are high, plan for a retrofit mitigation system.
• A new build in Hamilton, Guelph, or Kingston subject to the municipal program. Verify your obligations directly with the relevant City Building Department.
• Any home, anywhere in Canada. Health Canada recommends every home be tested. Geography and construction era are weak predictors. Testing is the only reliable answer.

How RadonTest.ca's kit works

• 91-day alpha track test — one day longer than Tarion's 3-month minimum. The detector can stay in place from 91 days up to 12 months (Health Canada considers 12 months optimal).
• Device approved by the Canadian National Radon Proficiency Program, analyzed by Lex Scientific (Guelph, Ontario) — Canadian lab, C-NRPP certified, ISO/IEC 17025 accredited.
• $89 all-inclusive: kit, both-way shipping, lab analysis, written report. No surprise return-postage fees, no US lab routing, no separate analysis charges. The kit, the test, and the result all stay in Canada.
• Heating season is best (October to April) but not required — long-term tests can be started any time of year. If you start outside heating season, consider running the test longer.

Order your test kit at radontest.ca → $89, all in →

9. Frequently asked questions

Does the Ontario Building Code require radon testing? No. The 2024 Ontario Building Code requires construction features (rough-in, soil gas barrier, sealed perimeter) but does not require radon testing of completed homes. Health Canada recommends every home be tested.

Does the 2024 Ontario Building Code guarantee my home's radon levels are below the Health Canada guideline? The 2024 Ontario Building Code makes your home easier to mitigate if needed — but it does not, on its own, guarantee your home's radon levels are below the Health Canada guideline of 200 Bq/m³. The rough-in is a capped pipe doing nothing. The only way to know your actual radon level is to test.

What's the difference between a rough-in, a passive stack, and active mitigation? A rough-in is a capped pipe stub through the slab with no air movement (Level 1). A passive stack extends that pipe through the building and terminates above the roof, using the natural thermal stack effect to draw soil gas out (Level 2). Active mitigation adds an in-line continuous-duty fan to the passive stack (Level 3). Most Canadian provincial codes require Level 1 today; the National Building Code 2025 moves the federal model to Level 2; some Ontario municipal programs (Hamilton, Guelph) come closer to Level 3 depending on building type and option chosen.

When does the National Building Code 2025 take effect in Ontario? The 2025 National Building Code was released by the Canadian Board for Harmonized Construction Codes on December 22, 2025. Ontario has not yet adopted it. Under the Canadian Free Trade Agreement reconciliation framework, provinces have approximately 18 months to adopt. Practical rollout in Ontario will likely take 1 to 3 years.

What if my radon test comes back below 200 Bq/m³? That's below the Health Canada guideline, so no remediation is required and no Tarion warranty claim is available. Re-test every 5 years or after any major renovation — radon levels can change as homes settle, soils shift, and ventilation systems age.

Does the Tarion warranty cover radon in resale homes? Yes, if the home is within its 7-year warranty window from the original possession date. The warranty travels with the home, not the original buyer. Contact Tarion to formally transfer the warranty into your name. See our Tarion radon warranty guide for details.

What test does Tarion accept for a radon warranty claim? A long-term test of at least 3 months (and up to 12 months), using a device or testing professional certified by the Canadian National Radon Proficiency Program, conducted in the basement. RadonTest.ca's 91-day alpha track kit, lab-analyzed by Lex Scientific (a Canadian C-NRPP certified, ISO/IEC 17025 accredited lab), meets both requirements. Order yours →

How much does radon mitigation cost? Active sub-slab depressurization systems typically cost $2,500 to $4,500 in Ontario when retrofitted into a simple basement. Complex homes — finished basements, multiple foundation levels, slab-on-grade foundations, or homes with very high pre-mitigation radon levels — can run $5,000 to $8,000. Homes with a rough-in already in place can be cheaper since much of the infrastructure is already installed. For Ontario homes under Tarion's 7-year warranty with a qualifying test above 200 Bq/m³, the cost is typically covered (up to $50,000 for purchase agreements signed February 1, 2021 or later).

Should I do my own post-mitigation test, or trust the mitigator's? A post-mitigation test is required to confirm the system actually brought levels below 200 Bq/m³. Mitigators typically run their own. Many homeowners run an independent test as well — it's a peace-of-mind step, and it gives you a clean third-party paper trail if questions ever arise. An independent post-mitigation test costs $89 with our kit. Order one →

Does Hamilton or Guelph require radon testing for new houses? Hamilton: depends on the construction option the builder chose — mandatory long-term post-construction testing applies for some Hamilton builder options under the City's three-option program. Verify directly with City of Hamilton Building Division. Guelph: as part of the changes introduced in the 2024 Ontario Building Code, post-construction radon gas testing is no longer required for new Part 9 residential buildings (single-family houses) under Guelph's program — these are now subject to the 2024 OBC provincial standard. Guelph's program continues to apply to ICI and Part 3 multi-residential buildings, with the certification form required for all new buildings and additions over 50 m². See our Radon in Guelph guide and Radon in Hamilton guide for details.

Is RadonTest.ca affiliated with Tarion or any municipality? No. RadonTest.ca is an independent Canadian radon test kit provider. We are not affiliated with, endorsed by, or licensed by the Tarion Warranty Corporation, the City of Hamilton, the City of Guelph, the City of Kingston, or any other municipality or regulator. Names of regulators and municipal programs are used in this article only descriptively.

Test your home. It's the only step the code doesn't take for you.

Order your RadonTest.ca kit → $89 all-inclusive

✅ 91-day long-term test — meets Tarion's 3-month minimum ✅ Device approved by the Canadian National Radon Proficiency Program ✅ Analyzed by Lex Scientific (Guelph, Ontario) — Canadian lab, C-NRPP certified, ISO/IEC 17025 accredited ✅ Written lab report — the document you attach to your builder notification and Tarion claim ✅ $89 all-inclusive: kit, both-way shipping, lab analysis, written report ✅ Stays in Canada from start to finish

Important disclaimers

This article is general information current as of May 2026. It is not legal, professional, or warranty advice.

Building codes and warranty rules change. Coverage amounts, eligibility, and procedural rules are determined by the original published instruments and by the administering authorities (provincial ministries, municipal building departments, Tarion, and the Home Construction Regulatory Authority). Where this article differs from a published rule, the published rule governs. Verify current rules directly with the relevant authority before relying on this article for a permit application, warranty claim, or transaction.

Municipal programs. Hamilton, Guelph, and Kingston municipal radon programs are subject to municipal bylaw and may evolve. Specific requirements, certification procedures, eligible building types, and permit closeout conditions are the relevant City's to define. Verify current requirements directly with the relevant City's Building Division before relying on this article for a specific build. RadonTest.ca does not administer any municipal program.

RadonTest.ca is independent from Tarion. We are not affiliated with, endorsed by, or licensed by the Tarion Warranty Corporation. The Tarion name is used in this article in a descriptive sense only, to identify Ontario's statutory new home warranty program. RadonTest.ca is not authorized to provide warranty advice or warranty assistance, and our role is limited to providing radon test kits and laboratory analysis through our partner Lex Scientific Inc.

Tarion qualification. Statements that a kit "qualifies" or "meets Tarion test-type criteria" mean only that the test method (long-term alpha-track, C-NRPP-listed device, lab-analyzed) matches Tarion's published test requirements. They are not a representation that any specific home, test, or claim will be approved. A complete Tarion radon warranty claim also requires that the home be within its 7-year warranty window, that the test result exceeds the Health Canada guideline of 200 Bq/m³, that the test be conducted in the basement (not a crawl space), and that the claim be filed correctly through Tarion's process. Tarion's published rules govern any specific claim — see our Tarion claim guide and tarion.com for the complete requirements.

Always verify directly with the relevant authority before relying on this information. For Tarion claims, visit tarion.com or call 1-877-9-TARION (1-877-982-7466). For Ontario Building Code questions, see ontario.ca/page/2024-ontario-building-code. For municipal radon program questions, see the relevant City's website. For Health Canada's radon guidance, see canada.ca/health-canada/radon. For radon testing protocol, consult the Canadian National Radon Proficiency Program at c-nrpp.ca.

Mitigation cost. The $2,500–$4,500 mitigation cost range is a typical Ontario residential figure. Actual costs vary by home, foundation, complexity, and contractor. Health Canada cites mitigation reductions of more than 80%; CARST cites up to 95%.

No diagnosis or treatment claims. RadonTest.ca sells radon test kits. We do not diagnose, treat, or prevent disease.

No warranty as to completeness. RadonTest.ca makes no warranty as to the completeness or accuracy of the information herein and accepts no liability for decisions made in reliance on this article. Readers should independently verify any information that bears on a transaction, a claim, or a construction decision.

Sources

Federal model code

• Canadian Board for Harmonized Construction Codes — 2025 National Model Codes (December 22, 2025)
• Canadian Board for Harmonized Construction Codes — Significant Technical Changes, 2025 National Model Codes
• National Research Council of Canada — Codes Canada publications

Health Canada

• Health Canada — Guide for Radon Measurements in Residential Dwellings
• Health Canada — Government of Canada Radon Guideline
• Health Canada — Radon Action Guide for Municipalities
• Health Canada — Radon: What You Need to Know (2025)

Ontario Building Code and Ontario regulators

• Government of Ontario — 2024 Ontario Building Code
• Home Construction Regulatory Authority — Ontario Building Code Updates
• City of Hamilton — Residential Construction Requirements for Radon Gas Mitigation
• City of Guelph — Radon Gas Mitigation Program
• City of Kingston — Radon Gas Mitigation
• KFL&A Public Health — Test Your Home for Radon

Tarion Warranty Corporation

• Tarion — How your new home warranty protects you against the dangers of radon gas
• Tarion — Coverage and coverage limits after you move in
• Tarion — Purchaser & Homeowner FAQs
• Tarion MyHome portal

Industry standards and professional bodies

• CAN/CGSB-149.11-2019 — Radon control options for new construction in low-rise residential buildings (Canadian General Standards Board)
• Canadian Association of Radon Scientists and Technologists (CARST)
• Canadian National Radon Proficiency Program (C-NRPP) — Listed Professional Devices

Related RadonTest.ca articles

• How to Claim the Tarion Radon Warranty in Ontario (Up to $50,000 Coverage)
• Best Radon Test Kit in Canada (2026): An All-Canadian Alternative to AccuStar & Radonova, Compared
• Radon Testing When Buying or Selling a Home in Canada (2026)
• Long-Term Radon Test vs Continuous Digital Monitor (Canada, 2026)
• Symptoms of Radon Exposure: What Canadians Should Know
• What to Do If Your Radon Level Is Above 200 Bq/m³
• How Much Does Radon Mitigation Cost in Ontario?
• How to Read Your Radon Test Results
• Radon in Hamilton (2026)
• Radon in Guelph (2026)
• Radon in Kingston (2026)
• Radon in Ottawa (2026)
• Radon in Toronto (2026)