Chemical Exposure Assessment

What is chemical exposure assessment?

Chemical exposure monitoring measures the airborne concentration of solvent vapours, acid mists, process chemicals and reactive substances released during work that workers may breathe in during normal operations. It quantifies real personal exposure so employers can judge whether existing controls are adequate.

IndustrialAirMonitoring.uk provides independent chemical exposure assessment across chemical manufacturing, paint and coatings, printing, pharmaceutical, engineering sites throughout the UK. Our occupational hygienists deliver defensible exposure data that demonstrates compliance with the Control of Substances Hazardous to Health Regulations 2002 (COSHH) and the workplace exposure limits set out in HSE guidance note EH40.

Why chemical exposure assessment matters

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. Chemical exposure monitoring provides the objective evidence that satisfies this duty.

Uncontrolled exposure to chemical exposure is linked to narcosis, respiratory sensitisation, organ damage and chemical 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.

How we carry out chemical exposure assessment

We measure exposure using sorbent tubes, impingers and filters selected for each chemical, drawn through calibrated pumps, following the recognised MDHS 96 / MDHS 88 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.

Standards, limits and reporting

Chemical exposure 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.

Our chemical exposure assessment process

Our chemical exposure assessment programmes follow a structured, four-stage workflow so the results stand up to scrutiny. Request monitoring or book a site assessment to begin.

1Scoping & site survey. We review your processes, COSHH assessments and previous chemical exposure assessment data, then plan a representative sampling strategy using BS EN 689 similar exposure groups.
2On-site sampling. Qualified occupational hygienists carry out calibrated breathing-zone and static measurements across a representative shift, with full chain-of-custody documentation.
3Accredited analysis. Samples are analysed using the relevant MDHS / ISO laboratory method and the results are compared against the applicable workplace exposure limit.
4Reporting & recommendations. You receive a clear exposure report with compliance status, control recommendations and a re-monitoring interval — defensible evidence for HSE, insurers and auditors.

Frequently asked questions

What chemicals can you assess?

Solvents and VOCs, acid gases and mists, isocyanates, formaldehyde, metals and many process-specific substances — the media and method are matched to each chemical.

How do you choose the sampling method?

From the substances in your COSHH assessment and safety data sheets, we select the validated MDHS or ISO method for each chemical of concern.

What if a substance has no UK limit?

We benchmark against recognised international or manufacturer guidance values and the principle of reducing exposure to as low as reasonably practicable.