Dry ice is an incredible scientific material. In solid form, it can be used to rapidly freeze liquid-based materials and keep them frozen at ultra-low temperatures (ULT), for an extended period of time. Because dry ice is made of carbon dioxide, it is an environmentally friendly way to manage the byproducts of petroleum production, it is easy to manufacture, and has been used for decades. Today, dry ice is frequently used in the transportation and distribution of perishable goods and even gets used in scientific laboratories to flash-freeze biological samples.

60 Minutes on CBS Nightly News recently covered a story on Operation Warp Speed investigating how Army General Gus Perna is preparing to inoculate 300 million Americans over the next few months. In the interview, General Perna expressed that he is most concerned about multi-dose vaccine requirements. It was described in this segment that Pfizer will be using dry-ice to support distribution of their vaccines, but how will these local clinics manage, store and guarantee effective administration of multiple doses of these vaccines? Is dry ice a great solution for local storage and administration? Probably not.

Dry ice while inexpensive, ultra-cold, and environmentally neutral, does unfortunately pose some serious health and handling risks. The Occupation Safety and Health Administration (OSHA) summarizes proper dry ice handling and management in this QuickFacts for Laboratory Safety (using) Cryogens and Dry Ice.

General Precautions When Working with Dry Ice:
  • Avoid eye or skin contact with these substances.
  • Never handle dry ice or LN2 with bare hands. Use cryogenic gloves, designed specifically for working in freezers below -80°C and for handling containers or vials stored in these freezers.
  • Always use appropriate eye protection.
  • Do not use or store dry ice or LN2 in confined areas, walk-in refrigerators, environmental chambers, rooms, or vehicles without ventilation. A leak in such an area could cause an oxygen-deficient atmosphere.
  • Never place 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.

So why were we able to experiment with these materials in our elementary-school science labs if they were this dangerous? The answer comes down to the amount of dry ice exposure. In small batches, with the correct PPE, dry ice is safe. If being used in larger volumes, for frozen storage – it must be replenished regularly to maintain ultra-low temperatures. Having replenishment stock on hand while working in small clinical rooms that were not designed for dry ice, could be very dangerous.

Dry ice sublimates at room temperature – using oxygen to emit CO2 into the atmosphere. Storage in a small room without ventilation, like you would see in a clinic or pharmacy, could lead to potential asphyxiation. Dry ice is so cold it can cause serious skin burns if the correct gloves are not used, and goggles and/or face shields must be worn to prevent any contact with the eyes.

With dry ice demand steadily increasing over the years, and less transportation vehicles on the roads due to COVID-19 lockdowns, dry ice manufacturers are reporting their material supply has decreased by almost 30%, causing an international shortage. This shortage will only intensify as the entire world tackles a herculean effort like COVID-19 vaccine release.

The last and final point that needs to be made about using dry ice for ultra-low temperature storage is that it is not a permanent solution or an exact science. Dry ice itself stays at -78°C, but whether it keeps the products thermally protected at that exact temperature while it sublimates, is not confirmed.

With advancements in cell and gene research and new regenerative medicines coming to market every day, ULT storage needs are most likely not going anywhere. And the manufacturers of these mRNA vaccines are still not sure how many doses will be required or even if this will turn into an annual vaccination like the flu shot.

Investing in non-consumable ULT storage infrastructure now will serve many healthcare operations well for the foreseeable future. Whether with a large, upright ULT freezer or a portable cooler-style freezer appliance, the need will remain. The table below summarizes how Stirling’s ultra-lightweight, portable ULT25NEU stands up to a dry-ice solution for ULT storage.

For more information on how Stirling Ultracold products are supporting COVID-19 vaccine efforts, our COVID-19 response page is regularly updated with the latest updates.