If you rent in Ontario and are worried about indoor air quality, radon is an invisible gas that can affect health over time. Tenants should know how radon testing works, what landlords are expected to do under provincial rules, and which official forms or boards can help if there is a problem. This guide explains simple testing options, practical steps to ask for remediation, and how to document concerns so you can protect your rights and health while living in a rental unit in Ontario.
Radon basics for tenants in Ontario
Radon is a naturally occurring radioactive gas that can build up inside homes and apartments. Health Canada recommends action if levels are at or above 200 becquerels per cubic metre (Bq/m3), and long-term (90+ day) testing gives the most reliable result.[1] If you live in a below-grade unit or an older building, testing is especially important because radon levels vary by building and local geology.
Who is responsible: landlord duties and tenant steps
In Ontario the Residential Tenancies Act, 2006 outlines repair and maintenance obligations for landlords; tenants also have duties to keep the unit in reasonable condition. If you suspect elevated radon, start by notifying your landlord in writing and requesting testing or remediation. Keep copies of all communications and any test photos or logs.
- Landlord must maintain the unit in a good state of repair, which can include mitigation if radon creates a health risk under habitability standards.
- Send a written notice to your landlord describing the problem, attaching photos and the date you first noticed issues; keep a copy for your records.
- If the landlord does not respond, note timelines and follow up within a reasonable period before seeking tribunal assistance.
You can find more about tenant and landlord responsibilities in our internal guide on Obligations of Landlords and Tenants: Rights and Responsibilities Explained, which explains common repair and notice steps.
Testing options and choosing a kit
Tenants can buy an approved long-term radon test kit or ask the landlord to arrange testing. Health Canada lists approved devices and testing guidance; many public health units also provide subsidized kits or advice. Place the test in the lowest lived-in level, follow kit instructions, and avoid short-term tests that last just a few days.
- Use a long-term (90+ day) kit placed in a main living area to capture seasonal variation.
- Record placement, dates, and any unusual ventilation events to strengthen your documentation.
- If results are at or above 200 Bq/m3, request mitigation measures such as improved ventilation or soil depressurization.
If you need to look for alternative rental options while remediation is arranged, you can also Find rental homes across Canada on Houseme.
What official steps can tenants take?
If the landlord refuses or delays, tenants can file an application with the Landlord and Tenant Board (LTB) to request orders for repairs or remediation; you will use the Board’s application process and supporting forms. The Board and provincial legislation can be referenced for formal remedies and timelines. For general guidance on health and safety topics in rentals, see our internal page Health and Safety Issues Every Tenant Should Know When Renting.
Practical example
Write to your landlord: state the radon concern, include test dates and results, request mitigation within a reasonable timeframe, and say you will apply to the LTB if the issue is not addressed. Keep all replies and receipts.
FAQ
- Do landlords have to test rental properties for radon in Ontario?
- There is no province-wide mandatory testing rule, but landlords must maintain habitability; if radon poses a health risk, remediation may be required under the Residential Tenancies Act.
- What radon level is considered dangerous?
- Health Canada recommends taking action at or above 200 Bq/m3 and suggests long-term testing to determine average exposure.[1]
- Can I test myself as a tenant?
- Yes. Tenants may buy or borrow long-term test kits, place them according to instructions, and share results with the landlord or use them when applying to the Landlord and Tenant Board.
- Where do I file a complaint if my landlord won’t act?
- You can apply to the Landlord and Tenant Board to request repairs or remediation; use the Board’s application forms and follow timelines for hearings.[3]
How-To
- Buy or borrow a long-term (90+ day) radon test kit and read the manufacturer instructions carefully.
- Place the kit in a lived-in area on the lowest occupied level, record the start date, and avoid disturbing it.
- After the test period, submit or send the device for lab analysis according to instructions and get the written result.
- If the result is at or above 200 Bq/m3, send a dated written request to your landlord asking for mitigation and include the test result.
- If the landlord does not act within a reasonable time, prepare documentation and file an application with the Landlord and Tenant Board.
