COVID-19 vaccines bring dry ice, cryogens into the forefront

Posted December 16, 2020

Most have read or heard the news about one of the approved COVID-19 vaccines needing to be kept at extremely cold temperatures. One of the ways to achieve this, particularly during shipping, is through the use of dry ice or cryogens.

Cryogens are substances used to produce very low temperatures [below -153°C (-243°F)], such as liquid nitrogen (LN2) which has a boiling point of -196°C (-321°F). Although not a cryogen, solid carbon dioxide or dry ice which converts directly to carbon dioxide gas at -78°C (-109°F) has similar properties.

Because dry ice is so prevalent these days (just think of the many ship-to-home meat and food products), it’s easy to overlook the hazards. Dry ice is actually quite dangerous if not handled properly.

One of the major hazards of dry ice is that it can “freeze” burn dry skin, so workers should never handle it without protection. Special gloves should be used. And, if there’s a potential for eye contact, eye protection and possibly a face shield must be used.

In addition, dry ice can displace oxygen posing a suffocation hazard – ventilation is key. Workers should never dispose of cryogens by pouring on a floor or on pavement.

Other general safety precautions when working with dry ice or LN2 include:

• Use cryogenic gloves, which are designed specifically for working in freezers below -80°C and for handling containers or vials stored in these freezers.
• Cryogenic gloves need to be loose-fitting so that they can be readily removed if LN2 splashes into them or a piece of dry ice falls into them. Alternatively, elastic-cuff insulated gloves may be appropriate.
• Never place a cryogen on tile or laminated counters because the adhesive will be destroyed.
• Never store a cryogen in a sealed, airtight container at a temperature above the boiling point of the cryogen; the pressure resulting from the production of gaseous carbon dioxide or nitrogen may lead to an explosion.

For more information about specific cryogens, read the Safety Data Sheet for the substance in question. And, remember, workers newly exposed to dry ice or cryogens must be trained under OSHA’s Hazard Communication (HazCom) standard, so they understand the hazards posed.

This article was written by Travis Rhoden of J. J. Keller & Associates, Inc.