Question 1

What is radon, and how does it enter my home?

Accepted Answer

Radon is a naturally occurring radioactive gas produced by the breakdown of uranium in soil and rock. It has no colour, odour, or taste. Radon seeps into homes through any available opening in the foundation — including cracks, construction joints, service pipe gaps, sump pits, and floor drains. Once inside, it can accumulate, particularly in lower levels with limited ventilation.

Question 2

Why is residential radon considered dangerous?

Accepted Answer

When radon decays, it releases radioactive particles that can be inhaled. Long-term exposure to elevated indoor radon concentrations is associated with an increased risk of lung cancer. Health Canada identifies radon as the second leading cause of lung cancer in Canada after smoking. The risk is related to both the concentration level and the duration of exposure.

Question 3

What is the current guideline for radon in Canada?

Accepted Answer

Health Canada recommends taking action to reduce radon when long-term indoor concentrations exceed 200 Bq/m³. The World Health Organization suggests a reference level of 100 Bq/m³. These are guidelines, not thresholds — the goal is to reduce radon exposure as much as practically possible. Testing is the only way to know your actual level.

Question 4

Can I rely on a 48-hour short-term test?

Accepted Answer

Short-term tests can provide a useful initial indication, particularly in time-sensitive situations. However, radon levels fluctuate depending on season, weather, ventilation patterns, and building pressurization. A 90-day long-term test is the Health Canada-recommended approach because it captures a more representative average over time, including seasonal variation.

Question 5

Are certain building types at higher risk?

Accepted Answer

Radon can be found in any building type, including detached homes, townhomes, semi-detached homes, and multi-unit buildings. Homes with basements, crawlspaces, or slab foundations are in direct contact with soil, which is the primary radon source. Airtight and energy-efficient homes can accumulate higher levels because natural air exchange is limited. The only way to assess risk for a specific building is to test.

Question 6

Why is residential radon considered a leading cause of lung cancer?

Accepted Answer

When radon decays in enclosed indoor spaces, it produces radioactive particles that can attach to dust and other airborne materials. These particles can be inhaled and settle in lung tissue. Long-term exposure at elevated concentrations is linked to cellular damage associated with lung cancer risk. The risk is cumulative — it relates to how much radon is present and how long exposure continues.

Question 7

Why do newer, energy-efficient homes often have high radon levels?

Accepted Answer

Modern construction techniques prioritize airtight building envelopes to reduce energy loss. While this is beneficial for energy efficiency, it significantly limits natural air exchange — which is one of the main ways radon dilutes and escapes. As a result, energy-efficient and newer homes can trap radon at higher concentrations than older, draftier buildings. Testing is especially important in newer construction.

Question 8

Where should a radon test be placed for maximum accuracy?

Accepted Answer

Health Canada and CNRPP guidelines specify that radon monitors should be placed in the lowest livable area of the home — typically the basement or lowest floor level where occupants regularly spend time. Monitors should be kept away from kitchens, bathrooms, laundry areas, windows, exterior doors, and air vents. Correct placement is essential for obtaining accurate results that reflect actual exposure in the living spaces.

Radon FAQ

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