Particulate is any matter dispersed in the atmosphere, whether solid or liquid, in which the individual particles are larger than single molecules (about 0.0002μ in diameter), but smaller than about 500μ. Settleable particulates, or dustfall, is normally in the size range greater than 10μ, and suspended particulates range below 10μ in diameter. For the purpose of this Subpart, the suspended and settleable particulates are as collected and measured by the method specified or other methods acceptable to the commissioner.