Occupational Safety and Health Administration Logs

What are the scientific or OSHA definitions of dust, fog, etc?

I'm reading the OSHA respiratory protection standard. It mentions "dust, fogs, fumes, mists, gases, smokes, sprays, or vapors". With biological safety we commonly refer to aerosols. There's also the (I'm guessing) general classification of particulates. Terms like these seem to often be used interchangeably. What are the official, legal, scientific definitions of words that describe these types of phenomena? There may be overlap between the terms above, or maybe more are needed. I want to be able to use them correctly when I write. And when somebody asks me!

Public Comments

1. The problem is that many of these terms have several definitions and are defined by the regulation and test method being discussed. Dust for example has more than 5 OSHA definitions. These definitions also change. Dust has changed several times in the last ten years. Smoke will be an EPA definition and definitions between EPA and OSHA don't always agree. Mist you will not find, but you will find oil mist in the regulations. You can find some info at the references, but the best method is to search for the regulation or test method and the definitions used therein.