PURPOSE:  Formulate control technologies to reduce miner exposure and determine associated occupational health risks through the identification of nanometer and ultrafine aerosols emitted by diesel-powered equipment.

RESEARCH SUMMARY:  More than 30,000 underground miners have been found to be exposed to diesel particulate matter (DPM) at levels as high as 500 µg/m3, an exceedingly high value. Recent promulgation of regulations by the Mine Safety and Health Administration (MSHA), limiting DPM exposures of underground miners, resulted in a swift implementation of novel technologies to control DPM and gaseous emissions. Control technologies, as well as modern diesel engines, were found to fundamentally change the physical, chemical, and toxicological properties of the emitted solid and gaseous aerosols. It is important to understand what these emissions are before prescribing solutions to control them.

In determining particle toxicity, past research has demonstrated the importance of parameters such as size, number, solubility, and surface area and chemistry. The effects that control technologies have on the physical and chemical properties and toxicity of nanometer and ultrafine diesel aerosols will be studied in a series of tests with the NIOSH Mobile Engine Dynamometer, both at the NIOSH Lake Lynn Laboratory experimental mine and at participating active mines. State-of-the-art instrumentation will be used to directly measure size distribution and number of nanometer and ultrafine aerosols. The chemical composition of these aerosols will be determined from the collected samples using proven analytical techniques. Genotoxicity analyses, performed by the NIOSH Health Effects Laboratory Division, will investigate the effects of control technologies on nanometer and ultrafine aerosol toxicity.

Results will provide industry, labor, and enforcement agencies with a better understanding of the physical and chemical properties and toxicity of diesel-generated nanometer and ultrafine aerosols. They will assess the effects that these properties have on workers’ health, particularly asthmatic and chronic obstructive pulmonary diseases. Researchers will generate information on the effects of various control technologies and modern diesel engines on the characteristics of aerosols and gases in mine air. These outputs should also result in a more sensitive, accurate, and relevant metric for monitoring the exposure of workers to DPM emissions. Ultimately, the industry’s acceptance of appropriately designed control technologies will reduce mineworkers’ exposure to nanometer and ultrafine aerosols.