Shoes must be worn at all times. There is often broken glass or spilled chemicals on the laboratory floor. Loose fitting clothes, especially long sleeves and neckties, are a definite safety hazard. They can easily fall into beakers or knock over a hazardous chemical. Long hair, if left hanging loosely, can be a real hazard.
Jewelry can also catch on protruding objects and lead to accidents.
Just drop your watch, rings, bracelets, and necklaces into a free pocket when you come to lab. Never place coats, books, or other belongings on the bench or floor where they will interfere with your work, be damaged by reagent spills, or pose a safety problem. Any experiment involving the use of, or production of, poisonous or irritating gases must be performed in the hoods. Food and beverages are not allowed in the laboratory. Use of all tobacco products in the lab is likewise not allowed.