Know the Risks – Work Safely with CO2
In addition to its vital role in photosynthesis, respiration and carbon cycle, carbon dioxide (CO2) has many industrial applications. Both solid and liquid CO2 are used in refrigeration and cooling. In the beverage industry, CO2 gives the fizz to the drinks and prevents bacterial and fungal growth in soft drinks, beer and wine. CO2 is an environmentally friendly propellant in aerosols and due to its unreactive nature it is used as an inert gas in various processes, packaging and fire extinguishers, to mention some applications. CO2 is produced in combustion processes of carbon containing material.
In addition to its excellent refrigerant properties, the safety and the non-flammable nature of CO2 have already been realized in the early days of refrigeration. CO2 is one of the natural refrigerants that does not harm the ozone layer and has no or negligible climate impact. CO2 has replaced the restricted CFC, HCFC and HFC refrigerants, which cause ozone depletion and are powerful greenhouse gases.
CO2 Exposure Limits in the Working Environment
CO2 is a non-toxic and non-flammable gas. However, it does not support life and exposure to elevated CO2 concentrations can induce a risk to life. The leakage of odorless and colorless CO2 refrigerant cannot be detected without proper sensors. Although CO2 is considered to be a non-toxic gas, CO2 concentration can reach dangerously high levels in poorly ventilated spaces.
There are guidelines and regulations related to the acceptable levels of CO2 in working environments. For example, the U.S. Occupational Safety & Health Administration, OSHA, has set limitation to CO2 exposure. The permissible exposure limit (PEL) describes the maximum daily human exposure to a substance allowed in a workroom’s air over an 8-hour shift. PEL for CO2 is 5 000 ppm measured as time weighted average (TWA) level of exposure. In addition, the American Conference of Governmental Industrial Hygienists, ACGIH, has set the short-term exposure limit to 30,000 ppm of CO2.
Risks of CO2
CO2 is always present in the atmosphere at a low level of approximately 400 ppm. However, high concentrations of CO2 are extremely dangerous. Drowsiness is experienced under continuous CO2 exposure at a level of 10,000 ppm (1%). At 2-3% of CO2 heaviness in the chest is experienced and breathing becomes more frequent and deeper. Headache and sweating will also develop during the exposure. Levels above 5% of CO2 are considered toxic.
At 4-5% of CO2, breathing becomes uncomfortable and lack of oxygen starts causing dizziness. At 6% of CO2 the sensory processing abilities start deteriorating after some minutes.
Less than one minute of exposure to 10-15% of CO2 results quickly in unconsciousness. When the CO2 level is between 17 and 30%, fatal exposure occurs in less than one minute. At all places where CO2 gas or CO2 ice is used, produced, shipped or stored, the levels of CO2 can rise dangerously high and the environment must be monitored with an appropriate sensor.
Selecting the Location for the CO2 Measurement
When measuring CO2 for the safety of the personnel, the CO2 transmitter should be installed as close as possible to potential leakage points for early detection. Transmitters should also be placed in all human occupied spaces. When designing the CO2 safety monitoring solution, the geometry of the monitored area should be considered, taking into account ventilation and air flow in the space. The number and location of the CO2 transmitters should always be based on risk assessment of the monitored area. Get familiar with Vaisala’s reliable and accurate CO2 transmitters at www.vaisala.com/GMT220