Increasing the Accuracy and Resolution of Short-Term Ambient PM2.5, PM10 and PM-Coarse Measurements
The TEOM Series 1405-DF Dichotomous Particulate Matter (PM) Monitor is a new product development of Thermo Fisher Scientific. The instrument combines the field-proven technology of the TEOM Series 1400a Continuous PM Monitor and the Series 8500 FDMS Filter Dynamics Measurement System. This paper will present a discussion of how the FDMS / 1405-DF measurements are made and why this approach represents a major step forward in measuring PM-10, PM-2.5 and PM-coarse.
Thermo Fisher Scientific developed the Filter Dynamics Measurement System (FDMS® unit) to accomplish the challenging task of accounting for both the volatile and non-volatile components of PM, and reporting the combination as a mass concentration result. The FDMS sampling and measurement system is based upon a number of technologies successfully applied by Thermo Fisher Scientific, including the true-mass filter-based TEOM microbalance, a diffusion drying system, and a self-referencing technique to assess the volatile component of ambient PM. The FDMS unit provided a PM measurement approach that offers the ability to quantify more representatively the PM mass concentration as it exists in ambient air taking into account the dynamics of PM that has been deposited on a sample collection filter, and how that material behaves over time.
The Series 1405-DF takes advantage of the FDMS development and combines a virtual impactor with a dual filter mass transducer to provide high-quality, representative PM mass concentration readings for both short-term averages (one hour) as well as 24-hour averages. Using the FDMS approach and incorporating the traditional low volume virtual impactor that has been used on the Thermo Scientific's Model SA-241, Partisol Model 2025-D, and Partisol Model 2000-D Dichotomous Air Samplers, the Series 1405-DF monitor offers air pollution investigators and agencies a single, network-ready, measurement system that can continuously sample and analyze PM-10, PM-2.5 and PM-coarse, simultaneously.
A prototype of the new monitor participated in EPA field trials in Phoenix and Birmingham during 2005-2006 and the final design is currently undergoing testing to support an application to the US EPA for designation as a Class III Equivalent Monitor for PM10, PM2.5 and PM-coarse. The paper includes a summary of recent test results to demonstrate the short term measurement capability of the instrument.