When living creatures exhale, they give off carbon dioxide(CO2) gas.
In simple terms, under high pressure and low temperature, CO2 gas becomes a liquid. Take this liquid CO2, release the pressure, and the expansion of the liquid and the high speed evaporation of the CO2 cools the remainder of the liquid CO2 down to its freezing point, and you have frozen CO2 or dry ice.
Dry ice is extremely cold at -109 degrees F.!
Dry ice blast cleaning is hard work for those man-handling the pressure hoses and lines that are needed to do the cleaning. Add protective coveralls and face shields in a hot industrial environment, and those doing the work can get pretty hot.
How can they cool off? Well, they can find some pretty simple ways.