Ships of the desert. Camels were domesticated more than 3,000 years ago, and to this day, humans depend on them for transport across arid environments. They can easily carry an extra 200 pounds (90 kilograms) while walking 20 miles (32 kilometers) a day in the harsh desert.
Definition - What does Permissible Exposure Limit (PEL) mean? Permissible exposure limit (PEL) is the legal limit in the U.S. for maximum concentration of any chemical in the air to which a worker may be exposed continuously for eight hours without any danger to health and safety. PEL is established by the Occupational Safety and Health Administration (OSHA).
To be frank, the OSHA PEL is not the safe limit below which harm cannot occur. Rather it is the legal limit (i.e. what is âpermissibleâ), below which serious harm should not occur to most people. Thus, while the OSHA PEL represents the legal exposure limit, it does not necessarily represent the desired exposure level.