WAC 296-307-45015. Additional precautions if recirculating ventilation system exhaust air into the workplace

(1) The employer must only recirculate air that contains no substance at a concentration that could pose a health or safety hazard to employees; (2) The employer must make sure any exhaust system that recirculates air into the workplace: (a) Passes the air through a device that removes contaminants; (b) Sounds an alarm and automatically shuts down the dip tank operation, if the vapor concentration of any substance in the exhaust air exceeds twenty-five percent of its LFL; (c) Monitors the concentration of vapor from flammable or combustible liquids with approved equipment. Notes: 1. The LFL concentration in the air must be determined after the air passes through the air-cleaning device and before the air reenters the workspace. 2. Most substances will pose a health hazard at a concentration far below twenty-five percent of its LFL.