Maritime Occupational Health and Safety Regulations — 255
255 (1) An employee must not be exposed to a concentration of (a) an airborne chemical agent, other than airborne grain dust, airborne flour dust, and airborne asbestos fibres, in excess of the value for that chemical agent adopted by the most recent edition of the American Conference of Governmental Industrial Hygienists publication entitled Threshold Limit Values (TLVs) and Biological Exposure Indices (BEIs) ; (b) airborne grain dust in excess of 4 mg/m 3 ; (c) airborne flour dust in excess of 3 mg/m 3 ; or (d) an airborne hazardous substance, other than a chemical agent, that is hazardous to the health and safety of the employee. (1.1) An employer must ensure that an employee’s exposure to a concentration of airborne asbestos fibres is as close to zero as possible, but in any event the employer must ensure that the concentration does not exceed the value for airborne asbestos fibres adopted by the American Conference of Governmental Industrial Hygienists in its publication entitled Threshold Limit Values (TLV) and Biological Exposure Indices (BEI) , as amended from time to time. (2) If the concentration of an airborne chemical agent is likely to exceed the value referred to in paragraph (1)(a) or (b), if the concentration of airborne asbestos fibres is likely to exceed zero or if there is a concentration of an airborne hazardous substance that is hazardous to the health and safety of the employee, air samples must be taken by a qualified person and the concentration of the chemical agent, airborne asbestos fibres or hazardous substance must be determined in accordance with (a) the NIOSH standards set out in the 5 th edition of the NIOSH Manual of Analytical Methods (NMAM) ; (b) a method set out in the United States Federal Register, volume 40, number 33, dated February 18, 1975, as amended by volume 41, number 53, dated March 17, 1976; (c) a method that collects and analyzes a representative sample of the chemical agent with accuracy and with detection levels at least equal to those which would be obtained if the standards referred to in paragraph (a) were used; or (d) if no specific standards for the chemical agent are listed in the standards referred to in paragraph (a) and no method is available under paragraph (b) or (c), a scientifically proven method used to collect and analyze a representative sample of the chemical agent. (3) A paper or electronic record of each test made under subsection (2) must be kept by the employer on board the vessel where the concentration was sampled for a period of three years after the day on which the test was made. (4) A record must include (a) the date, time and location of the test; (b) the chemical agent for which the test was made; (c) the sampling and testing method used; (d) the result obtained; and (e) the name and occupation of the qualified person who made the test. (5) Subject to subsection (6), the concentration of an airborne chemical agent or combination of airborne chemical agents in a work place must be less than 50 per cent of the lower explosive limit of the chemical agent or combination of chemical agents. (6) If a source of ignition may ignite an airborne chemical agent or combination of airborne chemical agents in a work place, the concentration of the chemical agent or the combination of chemical agents must not exceed 10% of the lower explosive limit of the chemical agent or combination of chemical agents. SOR/2016-141, s. 58; SOR/2017-132, s. 14; SOR/2018-137, s. 2 SOR/2019-246, s. 338 SOR/2025-79, s. 30