Development of a sensitive real-time monitor for elemental composition of workplace aerosol particles

The best warning of human exposure to elevated toxic aerosol particles is a monitor that can provide a near-real-time alarm function. Use of surrogate indices such as particle- number concentration, mass concentration, and/or other flow-diagnostics variables is ineffective and could be costly when false positives do arise. We have developed a field- portable system specifically for monitoring beryllium particles in the air in near real-time. The prototype monitor is housed on a two-shelf handcart that can be used in workplaces involving beryllium extraction, machining, and parts fabrication. The measurement involves no sample preparation and generates no analytical waste. The operating principle of the monitor is laser-induced electricalplasma spectrometry assisted with aerosol-focusing technology. Performance data of the monitor indicates a dynamic range spanning over four orders-of- magnitude, and the monitor is capable of detecting an airborne beryllium concentration of 0.05 μg m ^-3. In reference, the Department of Energy standard for beryllium is 0.2 μg m ^-3 within an 8-hour average, while the Occupational Safety and Health Administration standard for beryllium is 2 μg m ^-3. In addition, the monitor is capable of simultaneous detection of multiple elements using an Echellette spectrometer. The capability of simultaneous detection provides a convenient means for positive identification, and possible quantification of multiple elements in near real time. We will present the beryllium results and show applications of the technology to simultaneous detection of several elements embedded in aerosol particles.