Workplace gas exposure does not announce itself. A refrigerant leak in a high-rise plant room, a build-up of carbon monoxide in a basement carpark, a pocket of hydrogen sulphide on a wellhead pad: every one of these is invisible, often odourless and capable of putting workers down before they realise something is wrong. Queensland businesses operating under the Work Health and Safety Act 2011 have a duty to identify hazards and implement a monitoring regime that catches them early.