71Specific control – atmosphere

71 Specific control – atmosphere (1) A person conducting a business or undertaking must ensure, in relation to work in a confined space, that: (a) purging or ventilation of any contaminant in the atmosphere of the space is carried out, so far as is reasonably practicable; and (b) pure oxygen or gas mixtures with oxygen in a concentration exceeding 21% by volume are not used for purging or ventilation of any airborne contaminant in the space. Work Health and Safety (National Uniform Legislation) Regulations 2011 83 (2) The person must ensure that, while work is being carried out in a confined space: (a) the atmosphere of the space has a safe oxygen level; or (b) if it is not reasonably practicable to comply with paragraph (a) and the atmosphere in the space has an oxygen level less than 19.5% by volume – any worker carrying out work in the space is provided with air supplied respiratory equipment. purging means the method used to displace any contaminant from a confined space. Notes for regulation 71 1 Regulation 44 applies to the use of personal protective equipment, including the equipment provided under subregulation (2). 2 Regulation 50 applies to airborne contaminants. 72 Specific control – flammable gases and vapours (1) A person conducting a business or undertaking must ensure, so far as is reasonably practicable, that while work is being carried out in a confined space, the concentration of any flammable gas, vapour or mist in the atmosphere of the space is less than 5% of its LEL. Work Health and Safety (National Uniform Legislation) Regulations 2011 84 (2) If it is not reasonably practicable to limit the atmospheric concentration of a flammable gas, vapour or mist in a confined space to less than 5% of its LEL and the atmospheric concentration of the flammable gas, vapour or mist in the space is: (a) equal to or greater than 5% but less than 10% of its LEL – the person must ensure that any worker is immediately removed from the space unless a suitably calibrated, continuous-monitoring flammable gas detector is used in the space; or (b) equal to or greater than 10% of its LEL – the person must ensure that any worker is immediately removed from the space.