Derivation and Use of Simple Relationships Between Aerodynamic and Optical Particle Measurements

Kori D. Moore
Randal S. Martin
William J. Bradford
Christian C. Marchant
Derek S. Jones
Michael D. Wojcik
Richard L. Pfeiffer
john H. Prueger
Jerry L. Hatfield


A simple relationship, referred to as a mass conversion factor (MCF), is presented to convert optically based particle measurements to mass concentration. It is calculated from filter-based samples and optical particle counter (OPC) data on a daily or sample period basis. The MCF allows for greater temporal and spatial mass concentration information than typical filter-based measurements. Results of MCF calculations from several field studies are summarized. Pairwise comparisons from a collocated study with multiple OPCs and mass samplers suggest the minimum variability of the MCF is 5–10%. The variability of the MCF within a sample period during a field study with distributed samplers averaged 17–21%. In addition, the precision of the Airmetrics MiniVol Portable Air Sampler for particulate matter (PM) was typically <10%. Comparisons with federal reference method (FRM) samplers showed that MiniVols yield PM2.5 concentrations essentially equivalent to FRMs with slightly greater deviations from the FRM for PM10 under tested ambient conditions