The dangers of carbon dioxide (CO2) are not widely understood. One of the most common questions we get are people asking what is the difference between carbon dioxide and carbon monoxide? Or they may wonder that if plants need CO2 to grow, why does the news report that high levels of CO2 are responsible for climate change?
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 of you who work and live in confined spaces, or work around tanks or cylinders of compressed CO2 gas or dry ice, CO2 can be dangerous. We here at CO2Meter have answers to some of the most common questions below.
What is CO2?
Carbon dioxide is commonly abbreviated as CO2 because it contains one carbon molecule paired with two oxygen molecules. It is a naturally occurring gas found in the earths atmosphere. It is colorless, odorless, and tasteless - indistinguishable by humans.
By volume, dry air contains approximately 78% nitrogen, 21% oxygen, 1% argon, but only 0.04% carbon dioxide and small amounts of other gases.
At 0.04% CO2 (400 parts per million) in fresh air, you will never have to worry about CO2.
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.
How much CO2 is dangerous?
In nature CO2 gas 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 3-5% of air making it dangerous.
The most common way CO2 can be dangerous, is through normal human respiration inside an enclosed environment.
Each exhaled breath contains about 3% CO2. As we breath in a sealed environment, oxygen is slowly converted into CO2. This level of CO2 can result in symptoms like dizziness, confusion, fatigue, vertigo, headaches, tinnitus, and even seizures or asphyxiation.
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 will also occur if the oxygen levels are outside of the safe zone. At levels 17 percent or below, your mental abilities become impaired.
Higher levels of CO2 can be life-threatening; and prolonged exposure to carbon dioxide can even cause a change in one's metabolism and bone density. The concentration of the gas, as well as the duration of exposure, determines the health effects.
Many CO2 related incidents have occurred in restaurants, breweries, indoor agriculture facilities, and stadiums to name a few. 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 occurs when breathing air with 5% or more CO2 by volume. The most common symptoms of carbon dioxide poisoning are headache, dizziness, weakness, chest pain, and confusion. In order to compensate the heart rate can increase to 300% of normal.
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.
Note that unlike CO2 gas, liquid or frozen CO2 (dry ice) is dangerous when handled. Proper insulated gloves and a face mask is recommended whenever handling dry ice.
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.
The overall agreed to CO2 exposure limits in the workplace by the NIOSH and OSHA are:
- 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.
Natural Out-gassing of CO2
A rarely occurring but possible way CO2 can be dangerous is a sudden out-gassing of CO2 from the ground.
Out-gassing 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 Leaks Indoors
CO2 can be dangerous in 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 death by CO2 leaks are rare, they do happen.
To ensure CO2 safety among individuals, customers, and employees worldwide, CO2Meter designed the CO2 Multi Sensor System which meets all codes including the NFPA, IFC, NFPA, the OSHA and NIOSH standards, and is designed to protect customers and workers near stored carbon dioxide.
Currently, state and local municipalities are continually writing updated codes that require the use of CO2 safety alarms in buildings where anywhere more than 100 lbs. of compressed CO2 is stored or produced.
CO2 Warning Signage
Any work areas around stored CO2 should 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.
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 meaning:
- Blue health hazard : 2 - Materials that, under emergency conditions, can cause temporary incapacitation or residual injury.
- Red fire hazard : 0 - Materials that will not burn under typical fire conditions
- Yellow instability : 0 - Material is normally stable, even under fire conditions.
- White specific hazard : SA - This denotes gas is a simple asphyxiant.
For more information, speak to a CO2Meter specialist at Sales@CO2Meter.com or (877) 678-4259.