Laboratory cold rooms are walk-in spaces mainly used by researchers to keep biological and chemical materials below room temperature. Although they are primarily for storage, cold rooms can also be used as work areas for temperature-sensitive experiments.
Cold rooms are typically not ventilated, and in most cases, air is 100% recirculated. Fresh air only enters the room when the door is opened. Because of this, as well as other design features, cold rooms pose unique safety concerns including those discussed below.
- Flammable liquids: Cold rooms are not appropriate for flammable storage because they lack proper ventilation, allowing for the buildup of flammable vapors. When these vapors come into contact with ignition sources like a thermostat, light switch, fan motor, or any electrical equipment inside the cold room, a fire or explosion can occur. Flammable materials should be kept in approved storage cabinets in well-ventilated areas. If they must be kept cold, they should be stored in flammable safe or explosion-proof refrigerators.
- Dry ice: This material is the solid form of carbon dioxide (CO2), and upon melting, it rapidly changes from a solid to a gas. Carbon dioxide gas is heavier than air and can displace oxygen, causing difficulty breathing and possible asphyxiation. Because of this, dry ice should only be handled and stored in a well-ventilated area and should never be used or stored in a cold room. For more information about dry ice safety check out our blog Spooky Season Safety with Dry Ice.
- Liquid nitrogen: This cryogenic liquid should never be stored in a cold room. However, it may need to be used in one for certain procedures. Because the cold room air is recirculated, there is the potential for nitrogen to displace oxygen, causing an oxygen-deficient atmosphere. If liquid nitrogen is being taken into a cold room for any reason, oxygen sensors should be present. Both a portable personal monitor that is worn on the lab coat and a room monitor with audible and visual alarms is recommended. As an additional precautionary measure, a door sign should also be placed on the outside of the cold room notifying others that liquid nitrogen is in use.
- Noise: Some cold room procedures may require the use of a sonicator or other loud equipment. If the unit isn’t equipped with an enclosure to mitigate noise, sound levels may become elevated as the cold room environment can amplify noise. In some cases, hearing protection such as earmuffs or earplugs and/or a Hearing Conservation Program may be required. Best practice is to post signage when a sonicator or other loud equipment is being used to prevent someone from entering.
- Cold stress/hypothermia: Cold rooms are normally kept at around 4°C (39°F); however, some cold rooms are set to temperatures as low as just under 2°C (35°F). Prolonged exposure to cold environments can cause the body to lose heat faster than it can be produced, leading to hypothermia. To prevent this, warm layered clothing should be worn under lab coats. In addition, wearing insulated gloves and a hat may be needed when working for extended periods of time. The National Institutes of Health (NIH) recommends taking a 10-minute break every 50 minutes when working in a cold room.
- Mold: Typical cold room environments are very conducive to mold growth. If mold isn’t prevented or mitigated promptly, it can result in contamination of research experiments. Spores can also be carried and spread to other areas of the facility. Researcher exposure to mold can lead to a variety of issues, including allergic reactions and respiratory symptoms such as sneezing, a runny nose, and wheezing, particularly for sensitive individuals. The storage of cardboard and paper should be minimized. Paper products that may be needed (e.g., Kimwipes®, paper towels) should be stored in a closed plastic or metal container.
Ultimately, cold room safety comes down to awareness and strict adherence to safe work practices. Hazard communication that includes specific signage and training is essential to mitigate the unique risks associated with cold room environments. For more information—contact us!
This blog was written by Beth Graham, Safety Partners’ Director of Quality, Research, and Training.
