In Minnesota, 2 in 5 homes has radon levels that pose a significant health risk, and nearly 80% of counties are rated high radon zones. Since radon is produced from soil, it is present nearly everywhere. Because soil is porous, radon gas is able to move up through the dirt and rocks and into the air we breathe. If allowed to accumulate, radon becomes a health concern.
RADON’S PATHWAYS INTO YOUR HOME
Since many Minnesota homes use their basements as livingspace, exposure to radon can be further increased. But any home can have a radon problem, no matter what type of foundation it has and regardless of whether or not there is a basement.
- Cracks in concrete slabs
- Spaces behind brick veneer walls that rest on uncapped hollow-block foundations
- Pores and cracks in concrete blocks
- Floor-wall joints
- Exposed soil, as in a sump or crawl space
- Weeping (drain) tile, if drained to an open sump
- Mortar joints
- Loose fitting pipe penetrations
- Open tops of block walls
- Building materials: brick, concrete, rock
- Well water (not commonly a major source in Minnesota homes)Air pressures in your home
AIR PRESSURES IN YOUR HOME
Minnesota homes commonly operate under a negative air pressure, especially during the heating season. What this means is that the air pressure inside your home is typically lower then the surrounding air and soil, and this creates a vacuum that pulls soil gases, such as radon, into the home via pathways. Even if the ground around the house is frozen or soaked by rain, the gravel and disturbed ground underneath the house remains warm and permeable, attracting radon gas from the surrounding soil.
Other factors also contribute to air pressure changes in a home, including:
As warm air rises to the upper portions of a home, it is displaced by cooler, denser outside air. Some of that displaced air comes from the soil.
Combustion appliances like furnaces, hot water heaters and fireplaces, as well as exhaust fans and vents, can remove a considerable of air from a home. When air is exhausted, outside air enters the home to replace it. Some of this replacement air comes from the underlying soil.