June 5, 1996
A potential asphyxiation hazard exists when carbon dioxide is dispensed from tank cars (rail cars), cargo tanks (tank trucks and trailers), and portable containers to stationary, low pressure, carbon dioxide supply systems at consumer sites. These systems are used for supplying carbon dioxide gas at beverage dispensing sites, greenhouses, welding fabricators, and in other applications. High concentrations of CO2, which displaces oxygen, can result in death in less than 15 minutes.
The Cincinnati, Ohio Area Office recently brought to our attention the case of a delivery driver who succumbed to carbon dioxide asphyxiation while dispensing CO2 from his tractor-trailer. The driver, working for a restaurant supply company, pulled his trailer to the back of a restaurant at 1:30 a.m. to make deliveries of carbon dioxide and other supplies. This was a routine delivery for this driver as he made regular deliveries to this restaurant every five days at this time of night. The driver checked in with restaurant management and then proceeded to make his CO2 delivery. This involved taking the hose from the truck and connecting it to the restaurant's bulk CO2 system through a fill station located on the wall, below ground level, just outside the door to the basement.
After one-half hour, restaurant employees started to look for the driver and found him unconscious and lying face up at the bottom of the stairwell; they immediately called 911. The paramedical team had to use SCBAs to remove the victim from the stairwell. The paramedics were unable to revive him and he was declared dead at the local hospital.
The fill station was located in the below-ground stairwell, with a partial covering over the top of the doorway. The stairway and basement doorway were completely below grade.
The accident apparently resulted from a CO2 leak caused by an incomplete seal of the delivery mechanism where the hose from the truck's bulk system fastened to the fill connection (a fixed brass fitting) at the outside wall of the restaurant. This condition was exacerbated by the fact that the below grade location allowed the CO2 to accumulate without dissipation.
Carbon dioxide is a colorless, odorless gas and should be treated as a material with poor warning properties. It is denser than air and high concentrations can persist in open pits and other areas below grade. The current OSHA standard is 5000 ppm as an 8-hour time-weighted average (TWA) concentration.
Gaseous carbon dioxide is an asphyxiant. Concentrations of 10% (100,000 ppm) or more can produce unconsciousness or death. Lower concentrations may cause headache, sweating, rapid breathing, increased heartbeat, shortness of breath, dizziness, mental depression, visual disturbances or shaking. The seriousness of the latter symptoms is dependent on the concentration of carbon dioxide and the length of time the individual is exposed. The response to carbon dioxide inhalation varies greatly even in healthy normal individuals.
To minimize the development of hazardous conditions that may cause accidents or fatalities involving CO2 intoxication:
CAUTION - CARBON DIOXIDE GAS
Ventilate the Area.
A High CO2 Gas Concentration
May Occur in this Area
And May Cause Suffocation.
CGA G-6.5-1992, Standard for Small Stationary Low Pressure, Carbon Dioxide Supply Systems
CGA G-6.4-1992, Safe Transfer of Low Pressure Liquefied Carbon Dioxide in Cargo Tanks, Tank Cars, and Portable Containers
CGA G-6.3-1995, Carbon Dioxide Cylinder Filling and Handling Procedures
CGA G-6-1984, Carbon Dioxide
CGA G-6.2-1994, Commodity Specification for Carbon Dioxide
CGA G-6.6-1993, Standard for Elastomer-Type Carbon Dioxide Bulk Transfer Hose
Please distribute this bulletin to all Area Offices, State Plan States, Consultation Project Officers, and appropriate local labor and industrial associations.
1 The Directorate of Technical Support issues Hazard Information Bulletins (HIBs) in accordance with OSHA Instruction CPL 2.65 to provide relevant information regarding unrecognized or misunderstood health hazards, inadequacies of materials, devices, techniques, and safety engineering controls. HIBs are initiated based on information provided by the field staff, studies, reports and concerns expressed by safety and health professionals, employers, and the public. Information is compiled based on a thorough evaluation of available facts, literature and in coordination with appropriate parties. HIBs are used as an outreach tool for accident prevention.
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