Confined Space Gas Monitoring

Under COSHH Regulation 10, employers must monitor exposure to hazardous substances where it is needed to protect health, where a workplace exposure limit could be exceeded, or where control measures need to be verified. Confined space atmospheres monitoring provides the objective evidence that satisfies this duty.

Uncontrolled exposure to confined space atmospheres is linked to asphyxiation, explosion injuries and acute toxic poisoning. Beyond the legal duty, robust monitoring protects your workforce, reduces the risk of enforcement action and civil claims, and gives insurers and clients confidence that exposure is being actively managed.

We measure exposure using calibrated multi-gas detectors (O2, LEL, CO, H2S) with pre-entry and continuous monitoring, following the recognised Confined Spaces Regs 1997 methodology. Personal samplers are worn in the breathing zone for a representative full shift to derive an 8-hour time-weighted average, while static (background) samples help map contaminant sources across the workplace.

Samples are analysed by an accredited laboratory and the results compared with the relevant occupational exposure limit. Where short-term peaks are a concern we add 15-minute short-term exposure limit (STEL) sampling, so both the chronic and acute risk picture is captured.

Confined space atmospheres is controlled to as low as is reasonably practicable, with sampling benchmarked against published occupational and in-house standards. We assess compliance using the BS EN 689 statistical decision framework, which accounts for exposure variability rather than relying on a single result.

Your report sets out the measured concentrations, the compliance position, the adequacy of existing controls such as local exhaust ventilation, and a recommended re-monitoring interval. It is written to be understood by managers and to satisfy HSE inspectors, auditors and insurers.