Carbon Dioxide

What is carbon dioxide? Carbon dioxide (CO2) is a colorless, odorless, non-flammable gas that naturally occurs in the atmosphere. CO2 is produced by body metabolism and is a normal component of exhaled breath. It also results from the burning of fossil fuels and natural sources such as volcanic eruptions. CO2 levels in outdoor air typically range from 300 to 400 ppm (0.03% to 0.04%) but can be as high as 600-900 ppm in metropolitan areas. Although it is most commonly presentas a gas, CO2 can also exist in a solid (dry ice) form.

 

How are FSIS employees exposed to carbon dioxide? The most common exposure to CO2 for FSIS employees results from the off-gassing of CO2 gas from the use of dry ice for chilling and packing product. Dry ice is also sometimes blended with meat product. 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. However, levels at poultry plant inspection stations range from about 900 to 3,500 ppm (depending on how close the inspection station is to the dry ice use). In a few cases elevated levels, in excess of 5,000 ppm have been found at inspection stations.

 

CO2 gas is also used to euthanize both poultry and swine. This process is typically fully contained and CO2 is vented to the atmosphere (outside the building). In some cases, compressed CO2 gas is added to plant water (eg. chillers) to make carbonic acid for pH regulation. CO2 is denser than air and can collect in high concentrations in open pits, lowlying areas and confined spaces where it can displace oxygen creating a serious health hazard.

 

What are the health effects of carbon dioxide? CO2 is considered to be minimally toxic by inhalation. The primary health effects caused by CO2 are the result of its behavior as a simple asphyxiant. A simple asphyxiant is a gas which reduces or displaces the normal oxygen in breathing air. Symptoms of mild CO2 exposure may include headache and drowsiness. At higher levels,rapid breathing, confusion, increased cardiac output, elevated blood pressure and increased arrhythmias may occur. Breathing oxygen depleted air caused by extreme CO2 concentrations can lead to death by suffocation.

 

What are the symptoms of different levels of exposure? 5,000 ppm (0.5%) OSHA Permissible Exposure Limit (PEL) and ACGIH Threshold Limit Value (TLV) for 8-hour exposure ESHG-Health-02.00 FSIS Environmental, Safety and Health Group Carbon Dioxide Health Hazard Information Sheet 10,000 ppm (1.0%) Typically no effects, possible drowsiness 15,000 ppm (1.5%) Mild respiratory stimulation for some people 30,000 ppm (3.0%) Moderate respiratory stimulation, increased heart rate and blood pressure, ACGIH TLV-Short Term 40,000 ppm (4.0%) Immediately Dangerous to Life or Health (IDLH) 50,000 ppm (5.0%) Strong respiratory stimulation, dizziness, confusion, headache, shortness of breath 80,000 ppm (8.0%) Dimmed sight, sweating, tremor, unconsciousness, and possible death.

 

The response to CO2 inhalation various greatly even in healthy individuals. The seriousness of the symptoms is dependent on the concentration of CO2 and the length of time a person is exposed. Since CO2 is odorless and does not cause irritation, it is considered to have poor warning properties. Fortunately, conditions from low to moderate exposures are generally reversible when a person is removed from a high CO2 environment. Another health hazard caused by CO2 is frostbite by contact with solid CO2 (dry ice) and vapors off-gassing from dry ice. Precautions should be taken to prevent direct skin and eye contact with dry ice or with vessels/bins containing dry ice. Similar effects may occur from compressed CO2 gas as it is being released from a cylinder if it comes in contact with the skin or eyes. CO2 gas at room temperature will not injure the skin or eyes.

 

What OSHA standards and exposure guidelines apply? OSHA has established a Permissible Exposure Limit (PEL) for CO2 of 5,000 parts per million (ppm) (0.5% CO2 in air) averaged over an 8-hour work day (time-weighted average orTWA.) The American Conference of Governmental Industrial Hygienists (ACGIH) recommends an 8- hour TWA Threshold Limit Value (TLV) of 5,000 ppm and a Ceiling exposure limit (not to be exceeded) of 30,000 ppm for a 10-minute period. A value of 40,000 is considered immediately dangerous to life and health (IDLH value).

 

The TLVs are intended to minimize the potential for asphyxiation and undue metabolic stress. The ACGIH TLV supporting document states that: “Based on the long-term exposure studies, even though the majority of references are concerned with studies on physically fit males in confined spaces, a TLV-TWA of 5,000 ppm, is recommended. This value provides a good margin of safety from asphyxiation and from undue metabolic stress provided normal amounts of oxygen are present in the inhaled air.” The TLV-STEL is based on short-term studies which showed that “concentrations of 27,600 to 39,500 ppm produced increased pulmonary ventilation rates. Therefore, a TLV-STEL of 30,000 ppm is considered appropriate.”

 

How are occupational exposures monitored or measured? CO2 concentrations in air can be measured using detector tubes (for immediate short term samples) and passive indicator tubes or dosimeters (for longer TWA full or partial shift sampling). The primary OSHA method for the sampling and analysis of CO2 involves using a ESHG-Health-02.00 FSIS Environmental, Safety and Health Group Carbon Dioxide Health Hazard Information Sheet gas sampling bag followed by gas chromatography or infrared spectrophotometry analysis. If you would like to arrange for CO2 monitoring at your workplace, please contact your district’s Occupational Safety and Health Specialist.

 

What are the safety precautions protect for carbon dioxide? Employees should receive training and be knowledgeable of the potential sources and symptoms of exposure to CO2. If you are working near any sources of dry ice and develop any of the symptoms of exposure, move to an area of fresh air immediately, and report the incident to your supervisor. (Freshair or oxygen is the primary remedy for CO2 exposure. If you are pregnant consult with your supervisor and your physician about limiting exposure to CO2. If CO2 is used to euthanize poultry or livestock ensure that you are aware of the location of the gas sources and emission vents, alarm signals and any special precautions for working in those areas. Do not enter areas where CO2 levels exceed 20,000 ppm until ventilation has been providedto bring the concentration down to safe levels. Do not stand directly next to open bins that contain dry ice or in vapors from these bins. Donot touch dry ice or a bin containing dry ice.

 

How should training for this Health Hazard Information Sheet be recorded? Per requirements found in FSIS Directive 4791.1 Section IX, all occupational health and safety training is to be recorded using either AgLearn or FSIS form 3530-12. Training records are to include the topics covered, date, and employee name. The Agency is to retain all training records for a minimum of five years.”

 

Resources For more information, see the OSHA website: https://www.osha.gov/dts/chemicalsampling/data/CH_225400.html

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