You might think that the chemicals which apply to the rule are those in liquid, gas or particulate form. But, the standard’s definition of “chemical” is much broader than that commonly used. According to the HCS, chemicals that apply may exist in one of many forms:
Dusts – are finely divided particles. Example – wood dust.
Fumes – are even smaller particles usually formed when solid metal is heated and vaporized, and then condenses as tiny particles.
Fibers – are similar to dusts but are of an elongated shape. Examples – asbestos and fiberglass.
Mists – are liquid droplets that have been sprayed into the atmosphere.
Vapors – are gases formed when liquid evaporates.
Gases – are substances that are normally airborne at room temperature. A vapor is the gaseous phase of a substance which is a normally a liquid or solid at room temperature.