Dry Ice and Coolers: Keep Food Cold Without Trapping CO₂
How to use dry ice in an emergency cooler without cold burns, pressure buildup or unsafe food temperatures—and when to discard perishables.
Dry ice can keep food frozen in an insulated cooler during a prolonged outage, but it requires three controls: continuous gas venting, a barrier against direct contact, and a thermometer inside the cooler. Do not use an airtight cooler or keep it in an enclosed, poorly ventilated room.
The thresholds that decide what to do
| Check | Action |
|---|---|
| Perishable food is 40°F or below | Keep it cold and continue monitoring. |
| Frozen food still has ice crystals or is 40°F or below | It may be refrozen or cooked, although quality can decline. |
| Refrigerated perishables have been above 40°F for 4 hours or more | Discard them. Do not taste-test. |
| Cooler cannot release gas continuously | Do not put dry ice in it. Use regular ice or frozen gel packs instead. |
The FDA’s outage guidance supports the 40°F food-safety limit and four-hour discard rule. A cooler and new refrigerant do not erase the food’s earlier time above 40°F; if that history is unknown, take the safer course.
How to pack the cooler
- Use a dry-ice-compatible insulated cooler that lets gas escape. Dry ice changes directly into carbon dioxide gas. Never tape the lid shut, block a vent or add dry ice to a sealed inner container. Pressure can rupture a sealed container, according to Cornell Environment, Health and Safety.
- Wear dry, loose-fitting insulated gloves or use tongs. Ordinary disposable examination gloves are not enough thermal protection. Dry ice is about -109°F and can rapidly freeze skin.
- Keep food wrapped or in closed containers. Put cardboard or another insulating barrier between the dry ice and food; USDA says not to place dry ice in direct contact with food. For food you want to keep frozen, place the wrapped dry ice above the food rather than underneath it. USDA’s emergency guidance gives a planning benchmark of 50 pounds for an 18-cubic-foot freezer for two days, but that is not a dependable cooler-runtime formula.
- Add a thermometer and minimize openings. Keep frozen food tightly grouped. If you are protecting refrigerated—not frozen—food, increase separation from the dry ice because it can freeze nearby items. The New York State Department of Health specifically warns that dry ice may freeze food and advises keeping vulnerable items farther away.
- Use and store the cooler only with adequate ventilation. Do not put it in a basement, closet, sleeping area, walk-in cooler or closed vehicle. Carbon dioxide is colorless and odorless and can collect in low or poorly ventilated spaces. Headache, breathing difficulty, nausea or confusion are reasons to leave for fresh air and seek emergency help; do not re-enter a suspect space to retrieve the cooler.
There is no reliable “pounds per day” answer for every cooler. Cooler volume, insulation, how full it is, outdoor temperature, food starting temperature, dry-ice form and lid openings all change the result. Buy only the amount the dry-ice supplier recommends for your cooler and duration, then let the thermometer—not an estimate—decide whether food remains safe.
Transport and leftovers
Do not carry dry ice in an occupied passenger compartment. Use a separated, ventilated cargo area and minimize travel time; New York health officials also direct drivers transporting dry ice to keep vehicle windows open. Keep children and pets away.
Let unused dry ice disappear naturally in its vented container in a secure, well-ventilated place. Never put it in a sink, toilet, trash can or other confined container. See the separate dry ice disposal guide for the end-of-use setup.
A cooler is the better-defined use case here. Putting dry ice inside an appliance adds manufacturer-approval and appliance-damage questions; see dry ice in a refrigerator before considering that different setup.