Cold rooms and warm rooms are designed to control temperature and humidity in a confined space. Cold rooms are used primarily for storage and warm rooms are often used for bacterial culture, but both may be used as work areas for temperature-sensitive experiments. Both types of rooms are designed to function at non-ambient temperatures and are typically unventilated. These conditions present higher risk of certain types of hazards, such as presence of mold and work with volatile gases and asphyxiants that may displace oxygen. 

Guide to Cold and Warm Room Safety

Mold Hazard

Molds are part of the natural environment, and can be found everywhere, indoors and outdoors. Currently, Standards or Threshold Limit Values (TLVs) for airborne concentrations of mold, or mold spores, have not been set and there are no EPA regulations or standards for airborne mold contaminants.

That being said, unabated mold growth in cold and warm rooms can lead to contamination of research materials and pose a health hazard due to inhalation of spores. Molds produce allergens (substances that can cause allergic reactions) and irritants. Inhaling or touching mold or mold spores may cause allergic reactions in sensitive individuals. Allergic responses include hay fever-type symptoms, such as sneezing, runny nose, red eyes, and skin rash.

The best way to minimize mold growth is to control moisture and reduce possible surfaces for mold growth. Cold rooms are often more humid than warm rooms, though warm rooms can be humid and encourage mold growth. Of note, paper contains cellulose, which is a food source for many types of mold. It is therefore important to reduce or eliminate all cellulose sources in the room. This includes paper signage, paper storage boxes, cardboard shipping containers, absorbent materials like paper towels and chuck pads. Other non-cellulose-based surfaces may also harbor mold, so if there is a significant mold problem, it may be necessary to disinfect all surfaces of the room. 

If paper products must be stored in a cold room, place the item(s) in a closed plastic container between uses. 

Unventilated Spaces and Asphyxiant Hazard

Cold and warm rooms are often unventilated, with no fresh air being cycled into the space. Storage of volatile flammable liquids is prohibited in cold rooms, as flammable vapors may accumulate in the sealed room.

Storage of dry ice is prohibited in cold rooms. Dry ice is solid, frozen carbon dioxide. As dry ice sublimates, it turns into carbon dioxide gas, which can displace oxygen. In an unventilated room, this gas can build up. If enough carbon dioxide is present, a person can become unconscious and in some cases die. 

Other Physical Hazards and Egress

Doors to cold and warm rooms should be regularly tested for function. If the cold or warm room door is difficult to open, sticks, or the opening mechanism isn’t working stop use of the cold room immediately and contact facilities for repairs. Avoid storing items near the outside of the door to ensure egress at all times.

Keep floor clean of spills and debris in cold and warm rooms.  Liquid build up on the floor is a slip hazard. Some cold rooms may have low enough temperatures for ice formation, further increasing the chance for slipping. Promptly clean any spills and immediately report any leaks to facilities. Unnecessary items and debris on the floor are trip hazards and should be avoided.

Every Principal Investigator (PI) or user using a cold room is responsible for ensuring there is no mold growth on any of the user(s)' items. Label shelves, containers, and other items with the lab's name in shared spaces to establish clear ownership. Unlabeled items may be subject to being discarding during a clean-out. The following guidelines will help keep cold rooms mold-free: 

1. Do not store any porous or cellulose containing material, including cardboard and paper. Items like Kim Wipes and paper towels should be stored in airtight sealed containers when not in use. 
2. Use only metal or plastic shelving with adequate airflow. 
3. Do not store items on the floor of cold rooms or in sinks. 
4. Do not store food or drinks in the cold room. 
5. Clean any spills promptly; do not store materials that are excessively wet, as they raise the moisture content in the room. 
6. Keep waste containers outside the cold room. 
7. Report any water leaks, temperature issues, or other maintenance issues promptly to facilities. 
8. Keep the door shut firmly when not actively being used. 

All cleaning activities should be conducted in accordance with the University’s Chemical Hygiene Plan. Avoid the generation of aerosols. Soapy water refers to a mild detergent in water. When removing small amounts of mold growth warm soapy water should be substituted for an EPA approved biocide or fungicide used in a manner that follows the manufacturer’s instructions.

1. Wipe down interior of the cold room with a clean cloth and warm soapy water. Do not use abrasive scrubbers or chlorine cleaners.
2. Clean glass with a cloth and glass cleaner.
3. Wipe down the door gasket with a cloth and warm soapy water.
4. Remove excess items from the cold room. Discard any unwanted or expired items. Discard any material harboring mold growth.
5. Clean the shelves, cabinets, and counter tops with a cloth or soft brush and warm soapy water.
6. Sweep the interior of the cold room. Pay particular attention to removing debris from corners.
7. Clean the floors with a mop or brush and warm soapy water. Small areas can be cleaned using a clean cloth.
8. Clean the walls with a soft brush and warm soapy water.
9. Dry the walls carefully with a towel or cloth.
10. Apply sanitizer to surfaces for added protection if desired. Follow manufacturer’s instructions for specific product used.
11. Return necessary items back to the cold room.

• Hazardous chemicals- lack of exhaust ventilation can lead to increased exposure
• Flammable chemicals- exposed fan motors and electrical lab equipment can potentially ignite flammable vapors
• Acids and bases- corrosive vapors can damage refrigeration equipment and work surfaces
• Compressed gases- can displace oxygen due to limited ventilation, resulting in an oxygen-deficient environment
• Dry ice- like compressed gases, can create an oxygen-deficient environment

The EHS Office conducts annual laboratory safety inspections as a service to our research community. As part of our service, we offer suggestions to assist laboratories with compliance to federal, state, and local guidelines. 

EHS has developed a tiered ranking system for the severity of mold growth found in cold or warm rooms, summarized below. For levels 4 and 5, it is highly likely that EHS will require the lab or department to contract the services of a licensed mold remediation company. These services cost on average $3000-$5000 per room and lab personnel may still be responsible for identifying materials to be retained.