On Board Trains Occupational Health and Safety Regulations

7.21 (1) Subject to subsection (2), the concentration of an airborne chemical agent or combination of airborne chemical agents in a work place shall be less than 50 per cent of the lower explosive limit of the chemical agent or combination of chemical agents.

(2) Where a source of ignition may ignite the concentration of an airborne chemical agent or combination of airborne chemical agents in a work place, that concentration shall not exceed 10 per cent of the lower explosive limit of the chemical agent or combination of chemical agents.