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Gas Hazards in Commercial Cannabis Operations

By Karoly Ban Matei
Published: April 14, 2021
Key Takeaways

The cannabis industry is growing quickly, but it has yet to implement the kinds of controls needed to ensure the safety of its workers.

Caption: Cannabis Grower Source: OpenRangeStock / iStock

There are currently 36 states that allow the medical use of cannabis. 14 states now have made it legal to use it recreationally, while 16 have decriminalized it.

These numbers are likely to grow. Along with them, so will the number of commercial cannabis operations that will provide the supply to meet the demand.

This rapid growth brings the health and safety concerns associated with growing cannabis to the forefront. In a booming industry, there is a risk that growth will outpace the development and implementation of a robust health and safety system that can adequately control the hazards associated with cannabis production and cultivation.

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Cannabis operation present similar challenges and risks as other agricultural operations that rely on controlled enviornments. With cannabis, however, there are additional hazards introduced by the production of essential oils and extracts.

According to Cannabis Business Executive, among the first five OSHA citations for cannabis processors, four revolve around the use of controlled products, especially gases used in the growing and processing of cannabis.

Let’s start by looking at these hazards.

Carbon Dioxide Exposure

Carbon dioxide (CO2) is a gas that makes up a very small proportion of our atmosphere, with a current concentration of around 400 ppm. Plants need CO2 to sustain photosynthesis, and take in CO2 and water in order to produce glucose and oxygen. The glucose is used to fuel various cellular activities, which, in turn, fuel plant growth. Due to this crucial role, growers artificially increase the concentration of CO2 in the growing and production area up to 1,200 to 1,500 ppm.

This concentration should not pose a direct hazard to workers, since the OSHA 8 hours time-weighted average is 5,000 ppm and the Immediately Dangerous to Life and Health concentration is considered to be around 40,000 ppm. However, CO2 is heavier than air and will therefore settle in low-laying areas and displace oxygen unless there is proper ventillation. An atmosphere that is rich in CO2 and poor in oxygen can be very hazardous to worker’s life.

Carbon dioxide is also a hazard in extraction areas. CO2 in its liquid, gas, or dry ice form is often used in the extraction process, which is performed in self-contained cannabis extraction rooms.

One of these processes is supercritical CO2 extraction, which only uses carbon dioxide without adding other volatile solvents. This makes it a safer extraction method. However, even if this method eliminates explosive gases and vapors, the hazards of a high concentration CO2 environment remain and, as such, the concentration of the gas should be continuously monitored.

(Learn more in Gas Detection - Some Jobs Couldn't Be Done Without It)

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In subcritical CO2 extraction (also known as winterizing), a variety of solvents are used, which adds a risk of fire and explosion to the existing risk of a toxic or oxygen-deficient atmosphere.

Dry ice is also sometimes used in the extraction process. The main hazard of dry ice is that it quickly sublimates into its gas form, suddenly enriching with a large concentration of CO2 in poorly ventilated areas.

Fire

Fire poses another major hazard in commercial cannabis operations due to the various solvents that are used in the extraction process. The solvents remove the essential oils from plant material. This combination of solvents and essential oils is then further distilled to remove the solvent from the desired compound.

The solvents that are most commonly used in this process are:

  • Ethanol
  • Butane
  • Isopropyl alcohol
  • Heptane
  • Hexane
  • Toluene
  • Carbon dioxide

While CO2 is not technically a solvent, it is often referred as such when used in the extraction process.

Solvents are flammable and volatile and any increase in concentration in the extraction room could lead to a fire or an explosion if an ignition source is added to the mix.

This fire risk is not merely hypothetical. On June 19, 2018, Cal/OSHA cited Future2Labs Heath Services for an injury suffered by one of its employees. The employee was working alone inside a 128-square-foot portable storage container, using propane as a solvent to extract oil from cannabis. The propane ignited and exploded, leaving the employee badly burned and requiring several days of hospitalization. The company was cited with a total of ten violations, proposing fines adding up to $50,470. At the top of this list was the failure to protect employees working near flammable vapors.

Harmful Vapors

As discussed earlier, all the solvents used to produce cannabis-infused oils can produce harmful vapors.

A quick look at the OSHA, ACGIH, and NIOSH tables reveal that all these products have clearly defined exposure limits, which indicates that worker overexposure will result in severe adverse health effects and even death.

Exposure limits for solvents used in cannabis extraction

Gas Safety Best Practices

Carbon Dioxide

To eliminate or minimize the risk of CO2 over-exposure, growers and extractors should implement some industry best practices, such as:

  • Installing CO2 monitoring devices in all areas where CO2 might concentrate. In growing areas a CO2-only monitor will be sufficient. In extraction areas, however, a multi-gas device with LEL monitoring will be required.
  • Implementing engineering controls to maintain the concentration of CO2 below exposure levels. For example, connecting and calibrating the CO2 injection systems connected with the gas monitoring system.
  • Making the CO2 safety data sheet available to employees and ensuring that the hazards and controls for CO2 exposure are understood by the employees.
  • Wearing insulating gloves and safety glasses when handling dry ice, since dry ice is frozen at -79C (-109F) and can lead to severe frostbite on contact.
  • Avoiding the use of storage of dry ice in confined areas, walk-in refrigerators, environmental chambers, and rooms without ventilation. Dry ice sublimates from solid to ice very quickly as it warms up, so the released CO2 can create an oxygen-deficient or toxic atmosphere.

Best Practices for Fire and Vapors

Depending on their concentration and the presence of other hazards (like an open flame or electricity), the solvents used in the extraction process can either be a fire hazard or a health hazard. As such, I will address the best practices for these two in one list.

  • Extraction rooms should be designed for and dedicated to the extraction process. They should meet stated fire code regulations, including required suppression, gas detection, and ventilation systems.
  • The extraction equipment should meet the regulations put forth in the fire code that has jurisdiction in your area.
  • Electrical extraction equipment should have an engineering report certifying the electrical components are compliant with appropriate electrical standards and a National Recognized Testing Laboratory (NRTL) listing is required.
  • No vacuum ovens should not be used to process volatile gasses unless the vacuum oven is rated to process these vapors and is listed by an NRTL.

Summary

Despite its exponential growth, the cannabis industry is still in its infancy. This, combined with the use of flammable and toxic gases is almost bound to lead to an increase of injuries - especially from gas-related events, such as fire, explosions, and oxygen-deficient or toxic atmospheres.

A 2018 study published in the American Journal of Industrial Medicine revealed that far too few workers in the cannabis industry have received adequate training with respect to the hazards they may encounter on the job.

One of the best ways to compensate for these shortcomings is by making use of technology. The technology is evolving and controls for these hazards are already integrated into the design and build stages of these facilities, and gas detection and control devices will like be used as a fail-safe system, to provide redundancy and alert employees of hazardous conditions.

Cannabis growers and processors should understand their operations and invest in suppression and ventilation systems, as well as in gas detection and monitoring systems in order to provide a safe working environment for their employees. Doing anything less would be taking unnecessary and unwarranted risks.

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Written by Karoly Ban Matei | HR and Safety Manager

Profile Picture of Karoly Ban Matei

Karoly has worked at a senior level (both as an employee and a contractor) for organizations in the construction and manufacturing industries. He has a passion for developing and improving health and safety programs.

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