Where gases, liquids or solids in amounts exceeding the maximum allowable quantity per control area and having a hazard ranking of 3 or 4 in accordance with NFPA 704 are dispensed or used, mechanical exhaust ventilation shall be provided to capture fumes, mists or vapors at the point of generation.
Exception: Where it can be demonstrated that the gases, liquids or solids do not create harmful or flammable fumes, mists or vapors.