Development of a real time respirable coal dust and silica dust monitoring instrument based on photoacoustic spectroscopy

We report the first spectral photoacoustic measurements of silica, coal, and kaolinite dust absorption coefficients from 11 mu m to 13 mu m at 5 nm resolution made with a tunable quantum cascade laser. This is important because airborne silica dust and coal dust within mining environments continue to be a problem for mine workers and staff due to their severe health effects on the respiratory system, while other dust types are interferents. Our real-time spectra compare favorably with the filter-based Fourier Transform Infrared Spectrometer (FTIR) spectra obtained using the sampling system developed by NIOSH for their end-of-shift method to determine silica dust concentrations using a portable FTIR. We discuss our new dust generation system and instrument testing chamber. We also show that our PM4 silica mass concentration measurements by a low-cost air quality sensor (SPS30) are in good agreement with the TSI Aerosol Particle Sizer instrument and the NIOSH end of shift method.