ABSTRACT
There is a range of flammable, toxic and asphyxiating gases that might be encountered in the environment of a tunnel, particularly one driven through Coal Measures strata.
Flammable gases are, in the main, methane, carbon monoxide and hydrogen, but the actual presence depends on whether the tunnel is in the proximity of coal or ore. Carbon monoxide and hydrogen produced by the thermal decomposition of organic materials can be explosive and lead to dust explosions under generally dry conditions.
