The elements are exist in nature in the combined and the free state. The metals and non metals may combine with the other elements in the nature.
Lithium, potassium and sodium are the highest reactive element. If they present in the free state, they can explode in the air catches fire easily. This is the main reason that they never found in the free state in the nature.
While OSHA creates and enforces regulations, NIOSH focuses its attention on pushing the scientific field of occupational safety forward. They share the results of their research through robust education programs. They even provide workplace training to improve safety at businesses.