Do I need to carry out occupational exposure testing?

Yes — you may need to carry out occupational exposure testing if your workers could be exposed to hazardous substances in the air. It's a legal requirement in certain situations under COSHH (Control of Substances Hazardous to Health) regulations in the UK.
You Must Do Exposure Testing If:

1. You use or create harmful substances,
2. Exposure limits (WELs) might be approached or exceeded
3. You rely on control measures (like ventilation or PPE)
4. You can't be sure of exposure levels without measurement