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Dangers of CO2: What You Need to Know

co2 safety hazards

The dangers of carbon dioxide, commonly referred to as CO2 are not widely understood. Many people still confuse carbon dioxide and carbon monoxide. They also wonder why plants need CO2 to grow, yet the news reports that it is responsible for climate change and can even be hazardous.

Our goal is to separate the myths from the facts. Below is everything you need to know about the dangers of CO2.

Table of Contents

  1. What is CO2?
  2. What are the Dangers of CO2?
  3. How Much CO2 is Dangerous?
  4. CO2 Poisoning
  5. Is CO2 Flammable?
  6. Dry Ice Safety
  7. Natural Outgassing of CO2
  8. CO2 Exposure Limits
  9. How to Avoid CO2 Dangers and Overexposure
  10. What is a CO2 Alarm System?
  11. Importance of a CO2 Safety Alarm
  12. CO2 Warning Signs
  13. CO2 Safety Monitor & Alarm

What is CO2?

CO2 Molecule
  • CO2 is the chemical symbol for carbon dioxide. It contains one carbon molecule covalently bonded with two oxygen molecules. It is a naturally occurring gas found in the earth's atmosphere. It is colorless, odorless, and tasteless.
  • By volume, dry air contains approximately 78% nitrogen, 21% oxygen, 1% argon, but only 0.04% carbon dioxide. That's less than one half of 1 percent.
  • CO2 is part of the Carbon Cycle and is a requirement for life on Earth.
  • Because there is so little CO2 in fresh air, you will never have to worry about breathing too much CO2 outdoors.

Learn more about CO2 here.

What are the dangers of CO2?

From a "danger" or health perspective, in normal outdoor air, carbon dioxide is not a dangerous gas. Unless you live underground or in a submarine you'll never have to worry about it.

However, for those who work and live in confined spaces, or work around tanks or cylinders of compressed CO2 gas or dry ice, CO2 can be dangerous. For instance, exposure to CO2 can can produce a variety of negative health effects. These can include fatigue, difficulty breathing, nausea, asphyxiation, and in some cases, even fatalities.

Unfortunate events such as the Atlanta braves fatality and Smoky Mountain Opry, are both severe tragedies that could have been prevented with proper carbon dioxide safety monitoring. 

How much CO2 is dangerous?

In nature CO2 is only about 0.04% of the total volume of gases in fresh air. However, when changing from a liquid or solid to a gas it expands to 535 times its volume. This means that in an enclosed area, even a small leak in a CO2 tank or cylinder can quickly increase CO2 levels to 5% or more, which can lead to shortness of breath or suffocation.

While not dangerous, elevated CO2 levels indoors due to normal human respiration can affect humans. Each exhaled breath we take contains about 3% CO2. In an enclosed room, studies have shown that even at levels above 950 ppm CO2 leads to headaches, loss of concentration and lower test scores in students.

The Occupational Safety and Health Administration (OSHA) has determined the optimal breathing range to be between 19.5 and 23.5 percent oxygen. Serious side effects can occur if the oxygen levels are outside of the safe zone. At levels 17 percent or below, your mental abilities will become impaired.

When we discuss CO2 toxicity and dangers, studies also show problems when individuals are exposed to levels above 5,000 ppm for many hours.

Because of the use of compressed CO2 systems for beverages, an increasing number of CO2 related incidents have occurred in restaurants, breweries, indoor agriculture facilities, and stadiums that serve soda or beer. Always remember that in confined spaces or when breathing in a sealed environment, CO2 can quickly accumulate and your overall health could very well be at risk.

CO2 Poisoning


CO2 poisoning occurs when breathing air with 5% or more CO2 by volume. The most common symptoms of carbon dioxide poisoning are headaches, dizziness, weakness, chest pain, and confusion. If fresh air is not immediately available, suffocation can occur.

There are no known effects of gaseous CO2 contact with eyes or skin. While it is an odorless gas, many people describe the smell of higher levels of CO2 as a sharp or acidic. This is because the CO2 is creating carbonic acid in your body.

Unlike CO2 gas, liquid or frozen CO2 (called dry ice) is dangerous when handled. Proper insulated gloves and a face mask is recommended whenever handling dry ice.

Is CO2 flammable?

Carbon dioxide is a non-flammable gas. This makes CO2 increasingly popular as a refrigerant in the commercial, industrial, and fresh food transport industries. While liquid CO2 does not have the same thermodynamic properties as specialized refrigerant gases, it is good at heat transfer and relatively insensitive to pressure loss.

Dry Ice Safety

Dry ice is frozen CO2. Carbon dioxide, like water can be a solid, liquid or a gas depending on its temperature. While at room temperature CO2 is a gas, at -109.3°F (-78.5°C) it becomes a solid commonly called "dry ice."

Dry ice dangers include:

Freezing - the super-cold nature of dry ice makes it perfect as an alternative for water-based ice. However, because it is so cold, it will instantly freeze the skin. Therefore, dry ice should never be handled without proper gloves and safety precautions.

Melting - As dry ice melts or sublimates from a solid to a gas at room temperature, it quickly expands. In a confined space, the increased level of CO2 can displace the oxygen and make the air unbreathable.

Learn more about dry ice safety here.

Natural Outgassing of CO2


A rarely occurring but possible way CO2 can be dangerous is a sudden outgassing of CO2 from the Earth.

Outgassing is defined as the release of a gas that was dissolved, trapped, frozen or absorbed in some material.

Under the right conditions, mines, volcanoes, or fissures in the earth’s surface can suddenly leak tremendous quantities of CO2. The heavier-than-air carbon dioxide settles into low areas and becomes a death trap for anything living inside it.

For example, in 1986 at Lake Nyos in Cameroon, a large emitted cloud of CO2 suffocated 1,700 people and 3,500 livestock in nearby towns and villages.

CO2 Exposure Limits

To prevent additional incidents from occurring, CO2 standards and regulations have been created. The National Fire Protection Association (NFPA), the National Board Inspection Code (NBIC), and the International Fire Code (IFC) have all utilized recommendations from the Occupational Safety and Health Administration (OSHA) and the National Institute for Occupational Safety & Health (NIOSH) exposure limits to require carbon dioxide monitors to be set in place.

These parties all agreed to CO2 exposure limits in the workplace set by NIOSH and OSHA:

  • Short Term Exposure Limit (STEL): 30,000 ppm for 15 minutes
  • Long Term Exposure Limit (TWA): 5,000 ppm average over 8 hours

Other areas to be aware of in terms of CO2 exposure include:

  • Skin Contact - Liquefied CO2 or Dry Ice, can quickly burn and irritate the skin once contact is made. For safety, gently remove any clothing that may restrict circulation, loosely cover the affected areas with a sterile cloth and immediately call a poison center or doctor.
  • Eye Contact - When coming into contact with Liquefied CO2 or Dry Ice, immediately flush eyes with lukewarm water and cover both eyes with a sterile cloth. Treatment is urgently required.

Is Carbon Dioxide Harmful to Humans?

CO2 can be dangerous as a leak in a compressed CO2 system. Virtually every restaurant, bar or brewery in the country stores pressurized cylinders or tanks of carbon dioxide on premise. A CO2 leak inside an enclosed space, like the walk-in beer cooler, can become a potential death trap for anyone caught inside. While fatalities by CO2 leaks are rare, they do happen and individuals need to protect themselves while working around potential hazards.

Exposure to elevated levels of carbon dioxide can also cause symptoms such as dizziness, headache, shortness of breath, and in extreme cases, unconsciousness or death. High levels of CO2 can displace oxygen in the air, leading to oxygen deprivation, which is dangerous.

What does CO2 do to the body?

Exposure to high levels of carbon dioxide (CO2) can lead to several adverse effects on the body due to its impact on oxygen levels and the body's respiratory system:

  • Respiratory Distress: High levels of CO2 can interfere with the body's ability to exchange oxygen and carbon dioxide in the lungs. This can result in difficulty breathing, shortness of breath, and respiratory distress.
  • Headache and Dizziness: Increased CO2 levels can cause symptoms such as headache, dizziness, and lightheadedness. These symptoms may be the body's response to reduced oxygen intake.
  • Increased Heart Rate: In an attempt to compensate for reduced oxygen levels, the heart may start beating faster to deliver oxygen to vital organs. This increased heart rate can lead to palpitations and an elevated pulse.
  • Confusion and Disorientation: Prolonged exposure to high levels of CO2 can affect brain function, leading to confusion, disorientation, and impaired cognitive abilities.
  • Loss of Consciousness: In extreme cases, particularly when CO2 levels are very high, prolonged exposure can result in loss of consciousness or even death due to oxygen deprivation.

It's important to note that the severity of symptoms depends on the concentration and duration of CO2 exposure. Short-term exposure to moderately elevated levels may cause mild symptoms, while prolonged exposure to very high levels can be life-threatening.

6 steps to avoiding CO2 dangers:

  1. Never enter a workspace that stores or produces carbon dioxide without proper protective equipment, training or CO2 monitors. CO2, like ammonia, methane, or hydrogen sulfide can quickly cause loss of consciousness and death.
  2. Never use a CO2 fire extinguisher or dry ice in a manner by which it was not intended. If used indoors, open windows to allow for fresh air.
  3. In a business that uses compressed CO2, monitor and ventilate with CO2 safety monitors as required by code
  4. In a business that uses compressed CO2, never modify CO2 systems or tamper with equipment or alarms.
  5. Recognize and be aware of areas where CO2 can accumulate indoors.
  6. When in doubt, leave the area immediately or introduce fresh air.

What is a CO2 Safety Alarm System?

The primary purpose of a CO2 alarm system is to ensure the safety and well-being of occupants in enclosed spaces where elevated levels of CO2 could occur. Such spaces could include restaurants, breweries, wineries, walk-in coolers, grow rooms, industrial facilities, laboratories, and other CO2-producing areas.

CO2 alarms contain a non-dispersive infrared CO2 sensor that measures CO2 levels in real-time. A CO2 alarm system typically is equipped with both audible/visual alarm indicators or alarms, such as a loud siren or buzzer, as well as flashing lights or visual display. These indicators are designed to alert individuals when CO2 concentrations in a confined space exceed the normal threshold and provide immediate warning of high CO2.

It is worth noting that CO2 alarm systems are different from carbon monoxide (CO) alarm systems. A CO sensor cannot detect CO2. While both gases are harmful, they have distinct properties, sources, and health risks.

Importance of a CO2 Safety Alarm

The importance of a CO2 gas alarm lies in its ability to protect human health and ensure safety in environments where elevated levels of carbon dioxide can occur. Here are additional reasons why CO2 gas alarms are critical in the workplace:

  1. Health and Safety: Carbon dioxide is an asphyxiant gas, which means it can displace oxygen in the air and lead to oxygen deprivation. High levels of CO2 can cause symptoms such as headaches, dizziness, shortness of breath, and in extreme cases, loss of consciousness or death. CO2 gas alarms provide an early warning, allowing individuals to take immediate action to avoid prolonged exposure and potential health risks.

  2. Ventilation Monitoring: CO2 gas alarms can be particularly important in spaces where proper ventilation is crucial. Areas such as offices, classrooms, laboratories, or confined spaces may have limited airflow or be occupied by a large number of people, leading to increased carbon dioxide levels. Monitoring CO2 levels helps ensure that ventilation systems are functioning effectively or prompts individuals to take measures to improve air circulation.

  3. Indoor Air Quality: CO2 gas alarms can serve as indicators of overall indoor air quality, as well. High levels of carbon dioxide can be an indication of poor ventilation, the presence of other contaminants, or inadequate air exchange rates. By detecting elevated CO2 levels, alarm systems can prompt investigations into the root causes of the issue, leading to improvements in the indoor environment.

  4. Compliance with Regulations: In some jurisdictions or industries, there may be specific regulations or guidelines concerning CO2 levels in certain settings. CO2 gas alarms can help organizations comply with these regulations and maintain a safe working or living environment. Compliance not only ensures the well-being of occupants but also helps mitigate legal and liability risks.

  5. Early Warning System: CO2 gas alarms provide an early warning in the event of equipment malfunctions or leaks that may lead to an increase in carbon dioxide levels. This early detection allows for timely intervention, preventing potential accidents, property damage, or harm to individuals.

Overall, CO2 gas alarms play a crucial role in safeguarding human health, ensuring adequate ventilation, and maintaining a safe and comfortable environment in various settings. By alerting individuals to elevated CO2 levels, these alarms enable prompt action to mitigate risks and prevent potential harm.

CO2 Safety Warning Signs

Any work areas around stored CO2 should also have the proper safety signage in place. For example, this is the OSHA CO2 warning sign designed to be posted at the entrance of any room that contains tanks or cylinders of compressed CO2.

OSHA CO2 safety signage

In addition, the National Fire Prevention Association recommends an NFPA 704 diamond sign to warn first responders of the presence of CO2 before they enter a building or enclosed area.

NFPA 704 diamond sign for CO2

An NFPA 704 Diamond sign for CO2 means:

  • Blue health hazard : 3 - Can cause temporary incapacitation or injury.
  • Red fire hazard : 0 - Will not burn under typical fire conditions
  • Yellow instability : 0 - Normally stable, even under fire conditions.
  • White specific hazard : SA - This denotes gas is a simple asphyxiant.

What types of CO2 safety monitoring systems are available?

Remote CO2 Storage Safety 3 Alarm - CO2Meter

To ensure CO2 safety, customers use CO2 safety monitors like the Remote CO2 Storage Safety 3 Alarm. This device meets all codes including the NFPA, IFC, NBIC requirements, and the OSHA and NIOSH standards to protect customers and workers near hazardous carbon dioxide gas.

Because state and local municipalities are continually writing updated codes that require the use of CO2 safety alarms, these devices are also critical specifically in buildings where more than 100 lbs. of compressed CO2 is stored or produced.

Where should CO2 safety alarms be mounted?

Carbon dioxide gas is heavier than air. If a leak occurs, CO2 will always settle on the floor first. Then, like water, as the volume of CO2 increases the level will slowly rise.

If you have a low lying space near a CO2 tank, cylinder or CO2 system manifold, the CO2 gas will flow down the stairs and fill the basement before it will start to fill the main floor. In this case, you should have a safety monitor sensor 12 inches off the basement floor too.

While mounting the CO2 safety sensor 12 inches from the floor is best for early warning, it makes it difficult to read the CO2 level on the screen. This is why most CO2 safety alarms have 2 parts for installation and are mounted as follows:

  1. CO2 Safety Monitor Sensor - mounted near the gas 12 inches (32cm) from the floor

  2. Remote Display - mounted outside the door at 60 inches (152cm).

Note that while both of these devices include audible and visual alarms, the remote display is important because it warns staff before entering an enclosed area with high CO2 levels.

For more information on CO2 safety monitoring and Carbon Dioxide dangers, speak to a CO2Meter specialist at Sales@CO2Meter.com or (877) 678-4259.

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