There is no excuse for this type of accident today. Training by management and compliance by workers with the rules of safe working are essential to prevent such tragedies. I remember hearing years ago that workers in the UK who needed to enter manholes should bail out the space with a bucket, apparently to remove CO2 (from soil organism respiration). So, measuring the CO2 concentration in the tunnel atmosphere is also important, as it has no smell and only a few % is lethal. Furthermore, if hydrogen sulphide (H2S, bad eggs) can be smelled, it is especially dangerous, as it anaesthetises the smell receptors in the nose and, therefore, after a while it cannot be smelled anymore. It is still present, it has not dissipated but that is the perception.
Published by Mike Dempsey, Doctor
There is no excuse for this type of accident today. Training by management and compliance by workers with the rules of safe working are essential to prevent such tragedies. I remember hearing years ago that workers in the UK who needed to enter manholes should bail out the space with a bucket, apparently to remove CO2 (from soil organism respiration). So, measuring the CO2 concentration in the tunnel atmosphere is also important, as it has no smell and only a few % is lethal. Furthermore, if hydrogen sulphide (H2S, bad eggs) can be smelled, it is especially dangerous, as it anaesthetises the smell receptors in the nose and, therefore, after a while it cannot be smelled anymore. It is still present, it has not dissipated but that is the perception.