(6) Be sure that general ventilation, providing at least 10 room air
exchanges per hour, is provided in all area where mercury is used.
exhaust hood is required wherever mercury or an instrument containing
mercury is heated. Such hoods shall have an average air velocity of 150 fpm
through the fully open faces.
Fans for exhaust hoods shall be located at
the discharge point of the system.
(7) When pumps are used too pull a vacuum on a mercury reservoir, the
effluent air from the pumps should be discharged directly outdoors through
an adequate exhaust vent and an efficient trap should be placed between the
mercury reservoir and the pump; otherwise, the pumps may become heavily
contaminated with mercury and become a serious source of contamination.
(8) Accomplish the following whenever mercury is spilled:
(a) Deactivate equipment, give the alarm, and
systems which exhaust room air to the outside.
(b) Close vents and doors
vapors to enter other work areas
(c) Leave the area and take action to assure that personnel are
kept out of the contaminated area.
(d) Contact safety specialist and medical personnel to determine
the extent of contamination and corrective procedures to follow. A mercury
vapor detector will be used to monitor the air in areas where mercury
contamination is suspected.
Operations will not be resumed until the
concentration of mercury vapor drops below 0.05 milligram per cubic meter.
(f) Recover visible droplets of mercury with a mercury vacuum
cleaner, mercury scoop, or a suction device equipped with a water trap. The
contaminated areas should then be thoroughly scrubbed with soap and water.
If the area has cracks and crevices, it should be treated with a mercury
decontaminant, such as calcium polysulfide (Hqx or equivalent).
decontaminants do not remove mercury but coat the droplets and thus reduce
volatilization of the mercury. Monitoring of the area with a mercury vapor
detector should be performed to determine the thoroughness of the
(9) Personnel working regularly with mercury, or in areas where
mercury is used, should receive periodic medical surveillance including
determination of the level of mercury in the urine.