Mists are tiny droplets of liquid suspended in the air. For example, both spray painting and powerwashing produce mists. Fumes are solid particles that are formed when a metal or other solid vaporizes and the molecules condense in cold air. Welding and electroplating create fumes. Biological hazards, including bacteria, viruses, fungi, and other living organisms that can cause infections if inhaled, are also a form of air contaminants.
Gases are materials that exist as individual molecules in the air at room temperatures.
For example, the internal combustion engines on spray pumps produce carbon monoxide. The first three contaminants, dusts, mists, and vapors, are the most common respiratory contaminants found in a painter's workplace. For example, you might be prepping while a welder is working nearby on the same jobsite. Or, contrary to common sense, someone might bring a gasoline-operated spray pump or lift inside a building and expose you to deadly carbon monoxide. So, not only must you be aware of the particular respiratory hazards created by the work you are doing, but you must also be mindful of what others are doing around you.