2) Maintain controls. COSHH places specific duties on TRC to ensure that exposure controls are maintained. The objective being to ensure that every element of the control measure continues to perform as originally intended. This applies to items of equipment such as local exhaust ventilation and to systems of work, which will have to be regularly checked to make sure that they are still effective. Respiratory protective equipment should also be examined and, where appropriate, tested at suitable intervals. COSHH sets specific intervals between examinations for local exhaust ventilation