Can a safety video be dangerous? Yes, it can if it’s wrong, incomplete or misleading. It’s come to our notice that certain safety videos are in circulation which give at best incomplete advice on testing atmospheres for oxygen levels which could mislead seafarers into believing that an atmosphere is safe when, in fact, it is not.
Atmospheric air contains some 21 per cent oxygen by volume, a little more than we need to actually survive. Some safety videos suggest that atmospheres with oxygen levels between 19 and 20 per cent are safe because there is enough oxygen to support human life, which is true but misleading. If the atmosphere is significantly less than 21 per cent it means that something else is displacing the oxygen and that something else may be hazardous to your life.
If the oxygen levels are low, even by a percent or so, it may be wise to keep ventilation going until they are higher before entering the space.