The law requires business owners to assess the risks associated with any hazardous substances they use, and put in place specific controls to protect workers from exposure. This might include using personal protective equipment, providing training on how to handle hazardous substances safely, or installing ventilation systems.
If you're working with hazardous substances, it's important to know what COSHH is and how it applies to you. For more information, check out the HSE website or contact your local health and safety officer.