Mining Contract: PDM3700-Compatible Filter Module Usable with Portable/Field-deployable Silica Monitoring Instruments

Contract # 75D30121C11931
Start Date 9/1/2021
Research Concept

The objective of this project is to develop a filter module that can be used with the PDM3700, maintaining that instrument’s functionality of aerosol collection and mass measurement, and portable FTIR’s that can be used for NIOSH’s field-deployable silica monitoring technique.

Contract Status & Impact

This contract is ongoing. For more information on this contract, send a request to

Exposure to respirable crystalline silica (RCS) in mines poses significant dangers to mine workers, leading potentially to severe health conditions (e.g., silicosis) which oftentimes are fatal. Presently, monitoring of RCS in mines is done by on-site collection of dust particles on samples (filters) followed by off-site analysis by laboratories. Results are available typically after days or weeks. Thus, for some years there has been a push to develop on-site analysis techniques that could provide results more quickly (e.g., near-real time or end-of-shift (EoS)), allowing mines to respond more quickly to elevated exposures.

Thermo Fisher Scientific will develop a filter medium, hereinafter referred to as a “filter module”, since it consists of the filter material, a holder, and possibly additional supporting elements and an adaptor. The current filter is unsuitable for respirable crystalline determination, including: 1) the filter material (borosilicate glass microfibers reinforced with woven glass cloth) is a poor transmitter of IR radiation in the wavelength regime in which silica absorbs (transmissivity < 0.01), 2) the filter holder is constructed in such a way that its material framework would obstruct the IR pathway in the FTIR, and 3) the area on the filter over which the dust is collected may not be compatible with the IR radiation area within the FTIR. In designing a new filter module, we will take these issues into account. Additional issues for a new filter include: 1) allows for suitable air flow and pressure drop in the PDM3700 such that the filter material retains integrity, 2) aerosol retention percent during dust collection should be suitably close to 100% (presently 99.95% for TEOM filter), 3) dust should remain on filter during transfer from PDM3700 to FTIR, (4) sufficient particle loading capability, 5) suitably low uptake of unwanted gases, especially water vapor, and 6) suitable for scaling up for mass production.

Page last reviewed: 1/13/2022 Page last updated: 1/13/2022