Liquid and particulate aprons and smocks protect staff who work with splash hazardous and non-hazardous substances. Aprons have a waist tie closure and cover the front of the worker to the knee or lower. Sometimes called bib aprons, they are sleeveless and have an open back, making them cooler than garments that cover the front and back. Smocks have sleeves and cover the front and sometimes the back of a worker. They are knee length or longer.