Abstract
At most oil and gas sites, two decisions are made by different people. Engineers choose the gas detectors. Purchasing staff buy the respirators. The two choices are rarely compared with each other, and both are weaker as a result. This paper sets out a way to plan them together, from a single assessment of risk. The approach was built by reviewing published work in four areas: lung disease caused by breathing harmful substances at work, the materials used in gas sensors, how well respirators perform in real use, and the effect of a company's safety culture. It has four steps. Step one lists the harmful gases at each unit and the jobs that bring workers near them. It keeps everyday low concentrations separate from sudden releases. Step two sorts those situations into three risk levels. The levels are described in words, not in invented numbers. Step three sets the detection each level needs: the type of sensor, where it goes, and what each alarm means. Step four sets the respiratory protection the same level needs: the class of mask, the checks on how it fits, and the escape equipment that must be within reach. The paper then explains three things. Sensors behave differently in hot and humid air. Laboratory filter ratings promise more protection than a worker actually gets. And neither measure works if the organisation does not support it.