East St. Louis field performance evaluation of the thermo electron model 5030 SHARP PM_2.5 mass monitor

The Thermo Electron Synchronized Hybrid Ambient Real-Time Particulate Monitor (SHARP) is a PM_2.5 continuous mass monitor which incorporates the high time resolution of a nephelometer with the accuracy of beta attenuation. Two production version SHARP units have been running since April 2005 at the St. Louis - Midwest Supersite core monitoring location in East St. Louis, Illinois. We have previously reported on the SHARP measurement principles¹ and field performance in East St. Louis through the first nine months of testing . SHARP performance has now been evaluated for a full two years of operation in East St. Louis using the recently-promulgated Federal Equivalent Method (FEM) acceptance criteria as a frame of reference. For the one year period from May 2005 through April 2006, collocated precision was 1.4 μg/m³ (8%) for SHARP data collected at hourly resolution. Daily SHARP and FRM data were highly correlated. An unconstrained simple linear least squares regression of the 24-hour average SHARP mass on the 24-hour integrated FRM mass yielded slope 1.14 ± 0.02 (95% C.L.), and intercept 0.02 ±0.4 μg/m³ (95% C.L.) with a coefficient of linear determination of R²= 0.96 (N = 329). Operating conditions for one of the SHARP units were altered for the second year of operation, including changes to the sample preconditioning system hardware and control algorithm (not discussed in this extended abstract).