How Cold Is Dry Ice?

Dry ice reaches an extreme temperature of -78.5°C (-109.3°F) as it sublimates under standard atmospheric pressure. This temperature can drop even lower under certain conditions, which makes dry ice one of the coldest materials commonly used in industrial applications.

In this guide, we’ll explore the temperature properties of dry ice, as well as:

• The factors that influence its sublimation rate
• Safety considerations for responsible handling
• The key industrial applications that leverage the extreme cold of dry ice

WestAir supplies dry ice across California and Arizona.

What Is the Exact Temperature of Dry Ice?

Dry ice maintains a consistent sublimation temperature of -78.5°C (-109.3°F) at standard atmospheric pressure (1 atm). This temperature represents the equilibrium point where solid CO₂ transitions directly to gas without passing through a liquid phase.

The extreme cold results from the enthalpy of sublimation, measured at 246 BTU/lb (571 kJ/kg). Dry ice rapidly absorbs heat from its environment as it sublimates, creating its powerful cooling effect.

However, real-world conditions can push temperatures even lower. Excessive sublimation cooling can depress temperatures to -100.6°C under forced-air conditions, though this extreme is rare.

For reference, dry ice is about three times colder than a typical home freezer, which operates around -18°C (0°F).

What Factors Affect Dry Ice Temperature and Sublimation Rate?

The temperature and sublimation rate of dry ice are affected by the pellet size and surface area, container design and insulation, and ambient pressure conditions. Let’s have a closer look at these factors.

Pellet Size and Surface Area

Smaller dry ice pellets (3-10 mm diameter) sublimate faster than larger blocks due to higher surface-area-to-volume ratios. Testing has shown that pellets sublimate at a notably higher rate than blocks under identical conditions.

This accelerated sublimation intensifies cooling effects but reduces longevity.

Container Design and Insulation

Container integrity directly impacts thermal stability and sublimation rates. Reused containers increase sublimation rates due to micro-fractures that degrade insulation performance.

The FAA identified ‘Large Thermal’ containers as having the highest mass loss rate compared to other designs tested. Optimal packing requires using paper fillers to minimize dead space and slow sublimation by reducing gas convection.

Ambient Pressure Conditions

At aircraft cruising altitude (10.9 psia), sublimation rates can differ significantly compared to sea-level pressure (14.7 psia), though the exact relationship varies based on container and conditions. 

This pressure sensitivity makes dry ice particularly challenging for air transport. Humidity variations under typical conditions have limited impact on sublimation rates, making them secondary to pressure and design factors.

What Are the Safety Risks of Dry Ice?

The extreme cold of dry ice creates serious safety hazards like frostbite and asphyxiation, so this material requires careful handling protocols.

Frostbite and Skin Contact

Skin contact with dry ice at -78.5°C causes severe frostbite within seconds. The temperature is so cold that it can cause tissue damage similar to a severe burn, but from freezing rather than heat.

Always use insulated gloves and tongs when handling dry ice. Never allow direct skin contact, even for brief moments.

Asphyxiation from CO₂ Displacement

Sublimation displaces oxygen in confined spaces and creates dangerous CO₂ concentrations. High CO₂ concentrations can induce hypercapnia (a condition where there’s too much CO₂ in the bloodstream), which can lead to unconsciousness and death.

This is why proper ventilation is critical during storage and use. Never store dry ice in sealed containers, as gas expansion can cause explosions.

What Industrial Processes Use Dry Ice’s Extreme Cold?

Dry ice’s unique temperature properties make it essential for many industrial uses, from pharmaceutical shipping to preserving biological samples. Let’s explore the key use cases.

Biomedical and Pharmaceutical Shipping

The pharmaceutical industry relies on dry ice for shipping:

• Temperature-sensitive medications
• Laboratory samples
• Biological materials 

Vaccine transport leverages dry ice’s ability to maintain temperatures below -60°C consistently. This capability proved critical during COVID-19 vaccine distribution, where certain vaccines required ultra-cold storage.

However, sub-sublimation cooling can inadvertently freeze biologics below their stability thresholds. This is why temperature monitors are essential to prevent product damage from excessive cooling.

Industrial Cleaning

Cryogenic cleaning uses dry ice’s sublimation properties to remove contaminants without leaving residue. The solid pellets blast away surface contamination and then sublimate completely, leaving no secondary waste.

This process is particularly useful for processes like:

• Cleaning sensitive electronic components
• Removing paint and coatings
• Preparing surfaces for manufacturing processes

Scientific and Laboratory Applications

Laboratories use dry ice for calibrating low-temperature sensors and creating controlled cold environments for research. The consistent sublimation temperature provides a reliable reference point for scientific instruments.

Research facilities also use dry ice for:

• Preserving biological samples
• Creating inert atmospheres for chemical reactions
• Conducting materials testing at extreme temperatures

The material’s ability to maintain consistent temperatures makes it invaluable for quality control testing and research applications requiring precise temperature control.

Leverage the Extreme Cold of Dry Ice

Dry ice’s temperature of -78.5°C makes it an essential tool for industrial applications requiring extreme cold. While its consistent sublimation point provides reliable cooling, factors like pellet size, container design, and ambient pressure can significantly affect performance.

As industries continue to require more sophisticated cold chain solutions, understanding dry ice’s properties and safety requirements becomes increasingly important for optimizing its use in critical applications.

Lawrence Haynes

Currently serving as Marketing Director at WestAir Gases & Equipment in San Diego, CA Lawrence leverages his expertise in industrial gas solutions and equipment marketing. With a proven track record in cross-industry marketing strategy, he brings a specialized experience in content development, marketing automation, and partner relations to the industrial gas sector.