Radon and types of radiation
Radon is an invisible, odourless noble gas that enters homes in construction materials, domestic water and from the ground. This gas cannot be detected by ordinary gas chromatography, but is measurable because it is radioactive. Radon is the second-most common cause of lung cancer after smoking. In Sweden, if the radon content of all buildings measured as having a radon level exceeding 200Bq/m3 is reduced, we will ultimately be able to prevent around 200 lung cancer cases a year.
Types of radiation
- Alfa (α)
- Beta (β)
- Gamma (γ)
Where does the radiation come from?
How does radon enter a building?
The indoor radon content depends on activity (radium content) in walls, the airtightness of walling material, surface airtightness, the volume of the indoor space, indoor air change rate, air pressure, etc.
Ground water that mixes with water containing radium absorbs radon. Radon in domestic water is given off when water is run. This means that the radon content when we take a shower increases significantly. For municipal water, there may be no problem, but for properties served by a private well, the water may need to be aerated before it enters the building.
Radon gas may be sucked into a building from the ground beneath the property. With negative pressure in a ventilation system, the risk of radon infiltration increases.
Eliminating radon: what works?
If radon gas is emitted by structural materials in the building, and from these only, doubling the rate of ventilation halves the radon concentration.
Balance the ventilation system
For protection against ground radon, you need a balanced ventilation system, meaning the same amount of mechanical supply air as extract air. If there is negative pressure, the risk is that the radon will be ‘sucked’ into the building through cracks in the foundation. The solution for most homes is to install an air-to-air heat exchange ventilation system for venting spent, radon-contaminated air.More about air-to-air heat exchange ventilation systems