Mining Project: Develop Portable DPM Monitor

Research Summary

Diesel engines are one of the primary contributors to the presence of ultrafine and nano aerosols in ambient air and occupational environments. Exposure to diesel emissions has been shown to contribute to various adverse health outcomes of the pulmonary system and cardiovascular system. New technologies are being developed to reduce engine emissions and thereby airborne diesel particulate matter (DPM) levels, yet high exposures persist, especially in underground mines.

In order to reduce worker exposures, it is critical to measure the levels of DPM in the active work settings. In mine settings, exposures to DPM are measured by collecting air samples onto filters (usually full-shift samples), and sending them to a lab for subsequent analysis via the NIOSH 5040 method. This method is based on a thermal-optical technique and is independent of aerosol type and size, but has the significant limitation of being a laboratory method. Therefore, the time frame needed to collect samples, analyze them, and get quantitative results is usually days to weeks. This limitation makes it very difficult for mine safety personnel to utilize the results for effectively planning DPM reduction strategies. For this reason, this project research focused on investigating and developing alternative methods for measuring DPM in workplaces.

This project had four research aims, as described below.

1. Evaluate the use of Fourier transform infrared spectroscopy (FTIR) to quantify elemental carbon (EC) and organic carbon (OC) in filter samples derived from diesel tailpipe emissions and from mine air samples. This aim will include tasks designed to better understand the efficacy of using an existing spectrometry method that is well developed and understood, along with multi-variate analysis of the spectrometry data, to estimate the EC and OC in airborne diesel emissions.
2. Evaluate the use of laser-induced breakdown spectroscopy (LIBS) to quantify EC and OC in filter samples derived from diesel tailpipe emissions and from mine air samples. As with FTIR, this research includes tasks aimed at better understanding the efficacy of using an existing spectrometry method that is well developed and understood (i.e., LIBS), along with multi-variate analysis of the spectrometry data, to estimate the EC and OC in airborne diesel emissions.
3. Evaluate any existing measurement methods that have the potential to be applied toward the field-portable measurement of DPM. This may include, but is not limited to, black carbon extinction, thermo-optical analysis, Fourier transform infrared spectroscopy-attenuated total reflectance (FTIR-ATR), and particle scattering.
4. Design, build, and test a prototype DPM monitor with the intent to prove the concept in sufficient detail that the technology could be presented to a future licensee and eventually commercialized.

Because there is currently no field-portable method for measuring many airborne hazards, including the EC and OC that comprise DPM, demonstrating such methods represents a large leap forward in the measurement of human exposure to such hazards. The adoption of such a field-portable technology would enable workers, for the first time ever, to monitor their exposure to this toxic hazard.

Related Publication

Parks DA, Griffiths PR, Weakley AT, Miller AL [2021]. Quantifying elemental and organic carbon in diesel particulate matter by mid-infrared spectrometry. Aer Sci Tech 55(9):1014-1027.