Summary of Key Points

• Rural communities consistently exhibit over 30% higher radon exposure compared to more urban areas across all provinces and territories.
• Rural communities contain larger bungalows, contributing to the higher indoor air radon levels observed in these areas, compared to urban centres, where smaller multi-storey properties are more prevalent.
• The proximity of a residential house to a drilled groundwater well in rural communities unintentionally facilitates the migration of radon within “free-phase gas” that is deep-underground to surface-level soils significantly increasing the amount of radon underneath a building, and therefore increasing how much radon can be drawn up and inside.
• Prioritizing radon awareness and mitigation efforts can significantly contribute to the overall well-being of diverse communities across Canada.
• Radon gas, a naturally occurring radioactive gas, is known to pose a significant health risk when it accumulates inside our homes. Recent research has shed light on a surprising revelation: not all communities are equal in their exposure to radon.

A comprehensive study conducted over the past three years in Canada has uncovered substantial variations in residential radon exposure between urban and rural community settings.

People residing in more rural, lower-population communities experience as much as 31.2% greater average residential radon levels relative to their more urban, high-population equivalents. In turn, this equates to an additional 26.7 Bq/m³ excess radon in indoor air and a 20% increase in the amount of cancer-causing radiation dose absorbed by the lungs of the people living there. Our findings highlight a previously under-appreciated determinant of radon-induced lung cancer risk and support a need for targeted radon testing and reduction in rural communities. 

In Canada, evolving building practices over the 20th to 21st century have increasingly and unintentionally captured, contained, and concentrated radon within the residential built environment to unnaturally high and unsafe levels. 

The Evict Radon National Study team delved into Canadian residential radon gas exposure and our findings were unequivocal – rural communities consistently exhibited 30% higher levels of residential radon exposure compared to their urban counterparts across all Canadian provinces and territories. 

Factors Driving Radon Disparities

Our research aimed to unravel the mystery behind these disparities, and two key elements emerged as the primary contributors to elevated radon levels in rural areas:

Housing Characteristics: Rural communities are characterized by an increased prevalence of single-storey, single-detached houses with larger floor plans compared to urban areas, where smaller multi-storey and/or attached properties are more common. Larger, single-storey homes create an environment where radon gas is more likely to accumulate, elevating the risk for residents. 

Groundwater Wells as Gas Migration Pathways: A crucial revelation was the importance of the proximity and density of drilled groundwater wells near and around rural homes. These wells, vital for water access in many rural communities, unintentionally serve as faster free-phase gas migration pathways for deep-underground radon levels. Thus enabling radon gas to reach the upper layers of soil far more readily compared to areas where fewer to no drilled wells are present.

Drilled groundwater well completion regulations are less stringent compared to drilled wells in the energy industry, therefore their borehole annuli (the space that exists between the borehole and the well casing) likely provides free-phase gas pathways for the migration of radon gas in groundwater zones. Based on this knowledge, our team suggests that radon in rural community houses is relatively higher because of radon-rich gas migration (from deeper geologic sources) in drilled groundwater wells.

Many rural properties and communities rely on well water. Therefore, our researchers also tested the water for radon and found there was not enough radon in the well water to significantly contribute to the high radon being observed in indoor air. Instead, the problem appears to arise from the drill hole space existing around water well pipes. 

Implications and Recommendations

The implications of these findings are far-reaching, highlighting a community-based disparity in Canadian residential radon exposure. Our research underscores the urgent need for targeted radon awareness and reduction services in rural areas. Radon testing becomes imperative for rural communities, given the elevated health risks associated with prolonged exposure. 

It’s essential to note that while radon levels can be high in water wells, the primary concern lies not in the water but in the impact of drilled wells on the surrounding soil. This unintended consequence necessitates a shift in focus from water testing to soil testing to assess radon exposure risks accurately. 

Furthermore, residents in many rural Canadian communities already experience elevated risks of lung cancer, including those with reduced access to health care, groundwater arsenic exposure and an increased likelihood of smoking tobacco. Incorporating radon testing and mitigation measures becomes vital in comprehensive health strategies for these communities.

The unveiled rural-radon connection in Canada emphasizes the importance of understanding the nuanced factors contributing to residential radon exposure. Our research not only underscores the need for targeted interventions in rural communities but also serves as a reminder of the broader health challenges residents face in these areas. As we move forward, prioritizing radon awareness and mitigation efforts can play a pivotal role in ensuring the well-being of individuals living in diverse communities across the country.