Immediate Health Risks from Exposure to Carbon Dioxide

By B.W. Brandom, MD

Concerned Health Professionals of Pennsylvania

We have been living in carbon dioxide (CO2) our entire lives. How can that colorless, odorless gas be harmful? But the CO2 that living creatures produce and that plants use to make oxygen and carbohydrates is a gas at relatively low concentrations, ~ 0.04%, in our atmosphere. It is a different CO2, liquid CO2, that is lethal to humans. And at high concentrations CO2 gas is also potentially lethal.

Consider what happened in Satartia, Mississippi, the site of the first recognized exposure of an unprepared village to a CO2 pipeline failure.

In February 2020, after heavy rains and flooding, a 24-inch pipeline ruptured. It was carrying liquid carbon dioxide to be used for enhanced oil recovery. Satartia is a small rural town. It seemed to some that they had been attacked by a bomb, because of several, sudden loud noises. A cloud of smelly, green fog engulfed low lying areas. The smell and green color were due to contamination of the CO2 by 5% hydrogen sulfide in the salt cavern where it had been stored. Calls were made to 911. The first people found were unconscious in their car. They were barely breathing and had lost bowel & bladder function. Perhaps they were seizing before they were found. No one understood what was happening, so it was shocking when their cars stalled as they tried to escape the cloud. When oxygen in the air is diluted by high concentrations of CO2, internal combustion engines will fail.

Other unconscious and incoherent, confused people were rescued. At least 45 people got medical attention. EMTs evacuated over 200 people. One of the EMTs reported that without the airpacks provided by the volunteer fire department it was impossible to breathe inside the green cloud. Many residents still suffer physical and mental impairment from the effects of this exposure. Lung injury was permanent with the need for inhalers and supplemental oxygen, in some people. Reduced lung capacity was documented after exposure to this fog. Cognitive impairment has persisted in both elderly and young adults, as is to be expected after prolonged exposure to inadequate oxygen intake..

In addition to the danger from leaks, a lot of energy is used to compress CO2 gas into liquid that can flow through pipelines. This liquid CO2 has to be very cold and under very high pressure. The plans to make hydrogen out of methane must include capturing a lot of CO2 gas, turning it into liquid, and sending it somewhere underground, where it is presumed that it can not escape, in order to argue that this process produces less pollution. The process of making hydrogen with carbon capture and sequestration (CCS) causes more pollution and produces greater social costs than using solar energy to make electricity and hydrogen.

Because the US Department of Energy and the American Petroleum Institute have pushed for economic support, there are now proposals being prepared to take government funding (i.e. taxes that we all paid) to build hydrogen hubs with CCS. This will prompt preparing pipelines to move the liquid carbon dioxide from the industrial site where it was produced to the site where it will be deposited. It is time for us to learn about the danger that supercooled liquid CO2 under high pressure presents to us.

CO2 liquid is very corrosive. Any impurities, such as hydrogen sulfide, or water, in the liquid CO2 allow it to dissolve the inside of the pipeline even faster. Therefore, pipeline ruptures are to be expected. Because liquid CO2 is under very high pressure when it escapes from a pipeline it will expand rapidly. A cloud of CO2 gas can move many meters from the site of the break in the pipeline through which it escaped within seconds. When it first escapes a white cloud is visible. As it warms and expands further, it becomes an invisible gas. This invisible gas collects in high concentration in low lying areas because CO2 is heavier than air. Liquid CO2 is very cold. As CO2 expands outside a pipeline break, it will rapidly freeze water and tissues that contain water.

Although CO2 is not classified as a hazardous gas, OSHA considers CO2 hazardous. Where CO2 is used in industrial processes, there are lists of signs of CO2 toxicity and recommendations for what workers should do when levels of CO2 gas are higher than normal. If because of poor ventilation and/or release of CO2 by industrial processes CO2 toxicity occurs, it is important to recognize the cause of the symptoms and treat the affected person rapidly.

When the concentration of CO2 in the air reaches 1%, drowsiness may be its only effect. Above 1.5% CO2, faster breathing may be the only sign, although people vary in their responses to increased CO2. Above 3% the heart rate increases, the heart rhythm may become irregular and confusion or unconsciousness occur. The person, if they can still speak, may report a feeling of air hunger or suffocation. Headache, visual impairment, ringing in the ears, and disorientation are signs of CO2 toxicity as concentrations rise. Exposure to 4% CO2, 40,000 ppm, is an immediate threat to life. The effects of exposure to toxic levels of CO2 depend both on the duration of exposure and the concentration of CO2.

At concentrations of CO2 > 10%, convulsions, coma and death occur within minutes. This is because high concentrations of CO2 are directly toxic and because oxygen in the air is diluted. Normally the air we breathe contains 21% oxygen. People can function, although impaired, while breathing 14 to 18% oxygen, but as oxygen concentration falls both cardiovascular and neurologic systems fail. Obviously, the affected person should be removed from the toxic air as fast as possible. Four minutes of hypoxia can induce serious, often permanent, neurologic damage.

Workers, and citizens who expect to be exposed to such risks should have immediate access to self-contained breathing systems with supplemental oxygen (SCUBA). Training and practice are needed to use these systems safely and rapidly. In workplaces where the risk of carbon dioxide toxicity is recognized, immediate access to SCUBA is mandatory. CO2 reacts with water to produce carbonic acid. Thus, at very high levels of exposure to CO2 there can be risk of acid burns to eyes and mucous membranes. Knowledge of injury expected from exposure to failure of pipelines carrying liquid carbon dioxide is limited, because the existence of this type of accident has only recently been recognized.

In regard to the Satartia leak, The Des Moines Register reported that “among the violations cited, federal investigators said the company that ran the pipeline significantly underestimated the affected area that could be impacted by a release.” There was no warning sent out by the pipeline operators when low pressure was first detected. The rescuers knew little about expected effects of carbon dioxide toxicity. Local officials trying to rescue residents were the ones who figured out that it must be the CO2 pipeline that had failed. As the miles of pipelines in the USA carrying liquid carbon dioxide increase by orders of magnitude, as some planners suggest will happen, the risk of these accidents also increases. We must demand the preparation of emergency medical services and hospitals for such accidents.

I hope that this information helps you recognize the dangers of pipelines carrying liquid carbon dioxide. In the Midwest, groups are fighting to keep carbon dioxide pipelines from taking their farms by eminent domain. As Pennsylvanians face the construction of Hydrogen Hubs in our state, we must build awareness of the potential harm and design ways to avoid life-threatening risks.

B.W. Brandom, MD

Concerned Health Professionals of Pennsylvania

SOURCES

Howarth, RW, Jacobson, MZ. How green is blue hydrogen? Energy Sci Eng. 2021; 9: 1676– 1687. https://doi.org/10.1002/ese3.956

https://www.dnv.com/oilgas/laboratories-test-sites/dense-phase-spadeadam-video.html

(This is a video of a controlled leak of liquid CO2.)

Dan Zegart, Senior Investigator

Climate Investigations Center, www.climateinvestigations.org

The gassing of Satartia, Better Path Presents.