Precision of PM measurements with the UNC passive aerosol sampler

The UNC passive aerosol sampler measures concentrations and size distributions of indoor, outdoor, and occupational particulate matter. This study assessed the precision of passive sampler measurements using data from duplicate pairs of samplers that were deployed in a large field study. Particle count and size data were used to calculate PM2.5 and PM10-2.5 concentrations. To determine precision, the concentrations measured by duplicate samplers were compared to one another. Results showed that this sampler provides mass concentrations of PM2.5 and PM10-2.5 in the field with relative standard deviations that approach about 15%, with greater precision associated with higher concentrations (PM2.5>5 μg/m3 and PM10-2.5>20 μg/m3). Variability between measurements was associated with counting statistics and possibly with differences in the open area of the passive sampler mesh screen.

► Reasonable precision can be expected from the UNC Passive Aerosol Sampler.
► Measurement variability is attributed to counting statistics and mesh differences.
► Increased precision can be expected with longer deployment time.