Evaluation of aerosol-spectrometer based PM2.5 and PM10 mass concentration measurement using ambient-like model aerosols in the laboratory

Abstract

We have evaluated the PM10 and PM2.5 measurement using a Grimm 11-D optical particle size spectrometer (OPSS) with ambient-like aerosols generated in a laboratory. The ambient-like model aerosols include fresh soot, aged soot, ammonium sulfate, ammonium nitrate and Arizona Road Dust (ARD) particles. The mass concentration (MC) of test aerosols has been computed from the particle counts, equivalent particle volume and particle effective density using a proposed method. The expanded measurement uncertainties for the computed MC are estimated to be 27–36%, with detailed uncertainty analysis. The deviation of the computed MC from the reference gravimetric values is below 20% for MC levels from 29 to 1584 µg/m3. The computed MC agree with the reference MC within their measurement uncertainties. The underestimation and overestimation of the computed MC at various MC levels have been explained based on OPSS sizing errors related to the light-scattering and absorption property of the model aerosols. The proposed MC computation method is useful to evaluate the accuracy of OPSS in PM10 and PM2.5 measurement with the lab-generated model aerosols. This method can also be used to compare the performance of various OPSS-based PM monitors via inter-laboratory comparisons.