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Environmental Health & Safety


In the past, cold rooms for labs consisted of insulated boxes that did NOT have ventilation. Some of the newer cold rooms were provided with a small volume of fresh air to help ventilate the rooms. The supplied air was intended to prevent the buildup of carbon dioxide generated from personnel in the room as well as other contaminants that might be released in the room. Unfortunately, this small volume of supplied air created moisture problems contributing to mold growth, especially when trace contaminatns are present on surfaces. The result creates potential mold inhalation exposures for personnel.

Because cold rooms do not have ventilation systems, occupancy of cold rooms is limited to a total of two hours per 24 hour period (1 person for 2 hours, 2 people for 1 hour, etc.)


A number of health and safety problems can occur in cold rooms. These problems range from inhalation exposure of mold, unsafe use/storage of chemicals resulting in inhalation exposures, and storage of food and drinks in cold rooms resulting in potential ingestion exposures to molds. This document reflects good laboratory practices users of cold rooms are expected to follow.


The intention of cold rooms is to properly store certain agents and to conduct certain tests at a controlled temperature. Storing cellulose containing items can promote mold growth. Since biological and chemical agents are found in cold rooms, the potential for cross contamination of food and beverages can occur. To that extent, these guidelines are recommended to minimize mold growth, recommend correct chemical and biological use and storage, and list some activities that are prohibited.

Personnel can experience inhalation exposures to mold and a buildup of carbon dioxide when they are in cold rooms. EH&S’s Occupational Safety Unit (OSU) has tested the buildup of carbon dioxide in a cold room and determined that the OSHA Permissible Exposure Limit (PEL) for carbon dioxide of 5000 ppm is achieved when 4 individuals occupy a cold room continuously for a period of about 55 minutes. Although the OSHA PEL is for periods of 8-hours, OSU recommends personnel can occupy a cold room safely, based on the carbon dioxide level, for a period of 2 people-hours per day, to provide for variations in the size of the cold rooms.


Minimizing Potential Mold Growth

Mold has been found in many cold rooms. Every surface in a cold room can become contaminated with mold quickly should an improper work practice occur. The result is potential health problems from inhalation of the mold spores as well as contamination of research materials.

The storage of cellulose containing materials is a leading cause of mold growth. Mold growth can contribute to contamination of research materials. Preventing mold growth in cold rooms is achieved by controlling condensation/moisture and removing materials contributing to mold growth. The following actions need to be followed:

  • Promptly clean up spilled liquids (e.g., buffers, media). Mold can thrive on any organic medium.
  • Report water leaks to Facilities by calling x3-4567.
  • Keep door firmly shut to prevent condensation. Doors left open can increase the relative humidity in the rooms and promote mold growth. Placing a relative humidity (RH) gauge in the cold room and maintaining the RH at less than 60% helps to discourage mold growth.
  • Damaged door gaskets can provide a cold surface resulting in condensation problems. Watch for condensation on other surfaces as well. Condensation may be an indication of a loss of containment. Contact Facilities at x3-4567 for an evaluation of the problem.
  • Remove all wood. Wood shelves can absorb moisture and, because it is composed of cellulose, is a perfect breeding ground for mold. Wood shelves need to be replaced with open stainless steel shelves that permit air flow throughout the storage area.
  • Remove all cardboard and paper products. These surfaces act just like wood and promote mold growth. If some paper products (e.g., Kimwipes) are required, place them in a closed plastic container between uses. Should visible mold be found on a paper product, discard the item immediately.
  • Keep surfaces clean. Never use bleach on metal surfaces (bleach on metal surfaces can result in pitting). Wet cleanup activities are recommended (sweeping, dusting, or brushing will release mold into the air and can cause inhalation exposures and spread potential contamination).
    • If minor cleaning is needed, use a wet clean up method (e.g., dampen cloth with a non-ammoniated soap or detergent (do not mix ammonia and bleach; the fumes are toxic ). Dry surfaces after cleaning to ensure moisture has been removed.
    • If mold reappears soon after cleaning, use any hospital approved disinfectant, drying surfaces after cleaning to ensure moisture has been removed.
  • Place a label on the cold room door to remind users not to store paper/wood materials in the cold room as well as clean up small spills of materials soon after they happen.
  • Users will be held responsible for cleaning mold growth if EH&S inspections note improper actions that could contribute to mold growth.

Proper Chemical Use and Storage

Cold rooms are designed to recirculate the air contained within. Chemicals vaporizing into the air can accumulate and pose an inhalation exposure or an explosion hazard to personnel. Therefore:

  • Many flammable solvents can release sufficient vapors to form explosive atmospheres. These rooms have fans and electrical laboratory equipment that are potential ignition sources. Large quantities (>1 liter) of flammable solvents must NOT be stored in cold rooms. On a related issue, a standard refrigerator must never be used for the storage of flammable materials. Rather, flammable storage refrigerators need to be used.
  • Since cold rooms have a contained atmosphere, some hazardous chemicals that are not flammable may vaporize (e.g. chloroform, formaldehyde) causing exposures to personnel. The lab staff must consider this risk when evaluating the safety of their procedures and perform those procedures where vapors are released in a chemical fume hood. Quantities need to be limited to less than 250 ml (note: chemicals such as chloroform vaporize very quickly. Such chemicals should NOT be placed in squeeze dispenser bottles.
  • Spills of organic chemicals can occur in cold rooms. Prompt removal of the spilled materials is essential.


To ensure the safety of employees and students, the following activities are prohibited in cold rooms:

  • Beverage storage: In the past, EH&S has found alcoholic and non-alcoholic beverages stored in cold rooms. Such storage is unacceptable. Should EH&S note such storage, the issue will be reported to Security for immediate removal.
  • Food storage: Many food items can absorb chemical vapors that may be released into a cold room. To prevent the ingestion of possibly contaminated foods stored in this manner, personnel will be informed of the problem by EH&S with the expectation that the food will be removed immediately.
  • Compressed gas usage: Gases released from incubators and other devices in a cold room can result in a lowering of the oxygen level, resulting in possible asphyxiation. Gases should be used outside of a cold room. In the event gases must be used in a cold room, an oxygen sensor, equipped with a local alarm, must be installed in the cold room to warn staff should a low oxygen level occurs.
  • Never store dry ice in a walk in cooler. Dry ice can create an oxygen deficient atmosphere when it sublimes and releases gaseous carbon dioxide.


Because many cold rooms are shared between multiple groups, a single individual can create problems affecting all users. Should a problem be found, the designated responsible party or, if one is not appointed, all users must take the appropriate action to resolve the issue.

EH&S will notify users of cold rooms of improper use issues as we become aware of them.

Sample of cold room posting is available in pdf format:

Contact EH&S at (585) 275-3241 or e-mail EH&S Questions.

This page last updated 11/4/2011. Disclaimer.