<P> A thermal bag is a type of thermally insulated shipping container in the form of a bag which can be carried, usually made of thermally insulating materials . It is used to help maintain the temperature of its contents, keeping cold items cold, and hot items hot . </P> <P> Commercial thermal shopping bags, to carry temperature - sensitive purchases home without breaking the cold chain, were first introduced by grocery and other shops in Europe in the mid 1980s . A thermal bag to keep pizzas being delivered hot was invented by Ingrid Kosar in 1983, and is commonly used now . A cool box is very similar in concept, but typically larger and in the form of a rigid box . </P> <P> Thermal pharmaceutical bags are designed to transport temperature - sensitive medications, protecting them from damaging temperatures, shocks, and light . Many vaccines are delicate biological substances that can lose part or all of their effectiveness if they are frozen, allowed to get too hot, or exposed to bright light . Such vaccines must be kept within a specified temperature range, typically 2 to 8 ° C (36 to 46 ° F), from manufacture to use . According to the World Health Organisation, at least 7% of temperature - sensitive medical products suffer significant degradation in potency in transit . </P> <P> Thermal bags are usually manufactured with varying quantities of the following materials: </P>

How do you put a pizza in an insulated bag