Table 14.2.

CO2 concentration exposure categories for the diffuse degassing hazard maps

Soil CO2 concentrationEffects
CO2 vol%<1.5No hazard at any time
CO2 concentrations are those of non-volcanic areas.
1.5<CO2 vol%<5No risk of asphyxia
Weak soil degassing. No dangerous concentrations of CO2 in houses or spaces below ground.
5<CO2 vol%<25Low risk of asphyxia
Some evidence of CO2 contamination at bed level in houses. Lethal concentrations can be reached in non-ventilated spaces below ground.
25<CO2 vol%<50Moderate risk of asphyxia
Concentrations up to 1% CO2 commonly measured at bed levels in houses. Spaces below ground will accumulate lethal concentrations.
CO2 vol%>50High risk of asphyxia
Lethal concentrations of CO2 (>15%) were found at ground level in houses. All spaces below ground will accumulate lethal concentrations within a few hours.
  • According to Baubron et al. (1994) and Baxter et al. (1999).