Abstract: An inlet or primary particle size fractionator for a direct-reading PM2.5 mass sensor described herein may remove atmospheric particles of a given size, such as particles greater than the inlet cut point (e.g., having a 10 ?m AD cut point) and may transport particles less than the cut point to a mass sensing element or a secondary particle size fractionator (e.g., having a 2.5 ?m AD cut point). The inlet may have a flow rate range of between 1 mL/min and 50 mL/min (or higher flow rates depending on the application). The inlet may include a virtual impactor (VI), real impactor, cyclone, or virtual cyclone (VC). A sensing element may measure particle mass below the primary particle size fractionator (e.g., 2.5 ?m AD particles with a 10 ?m AD cut point inlet) and/or between the size range of the primary and secondary particle size fractionators (e.g., between 2.5 ?m and 10 ?m AD, or coarse particles).

Abstract: A multi-filter chemical speciation sampler and a virtual impaction particle separation inlet therefore are provided. The inlet includes a housing having a bottom, a collection tube that extends through the bottom, and collection apertures formed in the bottom, arranged around the collection tube; a first plate disposed on top of the housing, having acceleration nozzles disposed at the perimeter thereof; a second plate disposed in the housing below the first plate, having a central aperture and separation apertures disposed around the central aperture. The sampler includes: an inlet; a virtual impaction separator to further fractionate the PM into a course fraction and a fine fraction; a first separation assembly to divide the course fraction into coarse aliquots, comprising first filters to collect the coarse aliquots; a second separation assembly to divide the fine fraction into fine aliquots, comprising second filters to collect the fine aliquots.