Building and equipment areas protected by CO2fire extinguishing systems shall only be entered if absolutely necessary when such systems have been triggered. After a CO2 fire extinguishing system has been triggered there is a danger that persons in such areas may lose consciousness. Prior to starting work in areas protected by CO2 , a second person shall be notified and posted outside the hazard area to immediately initiate rescue measures if they become necessary. Immediately leave the hazard zone after completing work there.