Why do the hot packs smell?

Hot packs can smell due to the materials used in their construction, such as chemicals or substances that are released when heated. Additionally, if the packs are not cleaned properly or are stored in a damp environment, bacteria or mold may develop, contributing to unpleasant odors. Over time, the heating and cooling cycles can also cause degradation of the internal materials, leading to further smells. Regular maintenance and proper storage can help mitigate these odors.