The hazards of ground gases must be taken into account when designing and constructing new developments. Ground gas has can be drawn into a building by the pressure of difference that exists between the inside and outside of the building (warm indoor air is less dense than cold outdoor air).
Common ground gases and contaminates
Hydrocarbons – these can be highly toxic and are a derivative of the petrochemical industry. Hydrocarbons are prevalent in areas such as disused petrol stations and post-industrial sites. Most hydrocarbons are carcinogenic and potentially flammable.
Methane – An odourless flammable gas that is explosive when released to the atmosphere at levels as low as 5% and exposed to a source of ignition. Methane is formed wherever there is below ground degradation of organic substances e.g landfill sites, sewage treatment areas, mining localities and peat bogs.
Carbon Dioxide – a colourless, odourless gas that in high concentrations can result in asphyxiation. The gas is formed by the oxidation of carbon compounds such as landfill sites. When carbon dioxide levels reach concentrations of 3% symptoms of headaches and shortness of breath can occur, becoming severe at 5%, with loss of consciousness at 10%. It’s potentially fatal at concentrations of 22% and above.
Radon – a naturally occurring radioactive gas that is odourless and colourless. It is formed where uranium and radium are present. It migrates into any building that is built over the source. If it accumulates in a building at unacceptably high concentrations, it will increase the potential risk of the occupants developing lung cancer.