LAX Incident Highlights Dangers of CO2

As reported by Fox11 News in Los Angeles, on October 31, 2022, four workers at Los Angeles International Airport (LAX) became ill due to carbon dioxide (CO2) leaking from a fire-suppression system in an electrical utility room. One of the workers was hospitalized in critical condition. The entire terminal near where the leak occurred had to be evacuated. Some inbound flights were also impacted by the event.

The incident emphasizes the importance for facility management and personnel to be as vigilant regarding the levels of CO2 in their buildings as they are for carbon monoxide (CO).

According to the U.S. Department of Labor’s Occupational Safety and Health Administration (OSHA), just like CO, CO2, being odorless and colorless, is impossible for humans to detect and provides no warning of its presence. Exposure to the gas is potentially harmful and even deadly in certain circumstances.

How CO2 Causes Harm

CO2 can act as asphyxiant by reducing or displacing the normal oxygen in the air. Symptoms of mild CO2 exposure could include headache and drowsiness. At higher levels, rapid breathing, confusion, increased cardiac output, elevated blood pressure, and increased arrhythmias might occur. Breathing oxygen depleted air caused by extreme CO2 concentrations can lead to death by suffocation.

Levels of Exposure

The seriousness of the symptoms of CO2 exposure is dependent on the concentration of CO2 and the length of time a person is exposed. The OSHA Permissible Exposure Limit (PEL) and ACGIH Threshold Limit Value (TLV) for eight hours of exposure is 5,000 parts per million (ppm). At 10,000 ppm, symptoms such as drowsiness could appear. At 15,000 ppm, some people might experience mild respiratory issues. By 40,000 ppm, however, the level is high enough to threaten human life.

Breathing CO2 is not the only way a human can be harmed by the substance. Another is via frostbite, which can occur through by contact with solid CO2 (dry ice).

Causes of CO2 Exposure

There are various ways that workers can be exposed to CO2. One is from the gas produced from dry ice. CO2 levels directly next to an open bin of dry ice can be as high as 11,000 to 13,000 ppm. When dry ice is used in rooms without adequate ventilation CO2 has been measured as high as 25,000 to 30,000 ppm.

There are also systems that deliver CO2 to be used for applications such as beverage dispensing sites, greenhouses, and welding fabricators. The dispensing process can open the door to serious levels of exposure, as it did in the case of a delivery driver who succumbed to carbon dioxide asphyxiation while dispensing CO2 from his tractor-trailer to a restaurant’s bulk reserve. The accident was caused by an incomplete seal of the delivery mechanism where the hose from the truck’s system fastened to the fill connection on the restaurant’s outside wall. This situation was exacerbated by the system’s below-grade location, which allowed the CO2, which is heavier than air, to accumulate.

Keeping Workers Safe from CO2 Exposure

OSHA suggests taking the following steps to help protect workers from CO2 intoxication:

• Make sure that all personnel handling liquid CO2 or dry ice are thoroughly familiar with the associated hazards.
• When new CO2 receptacles are installed (as in new construction or remodeling), be sure that they are installed at ground level in an open area. If feasible, existing CO2 fill stations should be relocated to above-grade locations to prevent dangerous accumulations of the gas in below-grade areas.
• Adequately ventilate areas where CO2 is present to maintain a safe working environment for personnel. Since gaseous carbon dioxide is 1.5 times denser than air, it will be found in greater concentrations at low levels. Therefore, ventilation systems should be designed to exhaust from the lowest level and allow make-up air to enter at a higher point.
• Develop and implement a procedure to monitor the atmosphere for CO2 and provide local ventilation where levels may exceed the permissible exposure limit (PEL). Do not depend on measuring the oxygen content of the air because elevated levels of carbon dioxide can be toxic, even with adequate oxygen for life support.
• Affix appropriate warning signs outside of areas where high concentrations of carbon dioxide gas can accumulate.
• Establish a procedure for inspection and maintenance, at regular intervals, of all piping tubing, hoses, and fittings. The entire system should be maintained by qualified personnel in accordance with the manufacturer’s instructions.
• Ensure that there is adequate lighting to enable workers to use these systems safely.