Volatile organic compounds are present in many workplace environments, from printing and coating operations to laboratories, vehicle repair workshops, and food manufacturing facilities. Understanding when monitoring is required, what the results mean, and how to act on them is a practical necessity for employers with potential VOC exposure.

When monitoring is legally required

Under the Control of Substances Hazardous to Health Regulations 2002 (COSHH), employers must assess the risk from hazardous substances, including VOCs, and where a risk is identified, put in place adequate controls. Monitoring is not always legally mandated, but it is often the most defensible way to demonstrate that controls are effective and that exposures are below the Workplace Exposure Limits (WELs) set by the Health and Safety Executive. For processes that generate significant VOC emissions, monitoring is strongly recommended as part of the COSHH assessment.

Passive diffusion tubes versus active sampling

Passive diffusion tubes are the most practical method for routine workplace monitoring. A tube containing an adsorbent material is placed in the breathing zone of a worker or at a fixed monitoring point for a defined period, typically eight hours for a full shift exposure assessment. The tube is then sealed and sent to the laboratory for thermal desorption GC-MS analysis. Active sampling uses a pump to draw air through the adsorbent at a controlled flow rate, which gives a more precise result but requires more equipment in the field. We supply passive tubes, advise on placement, and collect them after the exposure period.

Interpreting results against WELs

Results are reported as a time-weighted average concentration in mg/m3 and ppm, and compared against the relevant eight-hour time-weighted average WEL from the HSE EH40 document. Where a result exceeds or approaches a WEL, the report notes this recommends review of engineering controls or personal protective equipment. We do not make enforcement decisions, but we write reports that are clear enough to inform them.

If you are unsure whether your workplace requires VOC monitoring, a brief conversation about the processes involved is usually enough to give a clear answer. Get in touch and we can advise on whether monitoring is appropriate and what it would involve.