Research Project
10140199
Abstract. Airviz Inc. is developing an affordable and reliable particle monitor that may be more relevant to adverse health outcomes by measuring both PM0.3 and PM2.5. While measurement of PM2.5 (particles smaller than 2.5µm) is the recognized standard for fine particle air pollution, there is a growing body of evidence to indicate that adverse health outcomes continue at levels less than half the average daily safe values of 12 ?g/m3 specified by the EPA. In 2005, Maynard and Kuempel concluded that particle toxicity increases with decreasing particle diameter and increasing total particle surface area, thus challenging mass-based risk evaluation approaches. Lung Deposited Surface Area (LDSA), 99% of which is due to particles below 300 nm, has been proposed as a better metric to relate PM exposures to adverse health outcomes. Attention has also been paid to relating mass concentrations of ultrafine particles (PM0.1, particles lower than 0.1µm) as a better health metric. But further studies indicate that measuring only ultrafine particles would exclude significant numbers of still very small particles and significant fractions of mass and surface, while measuring the contributions of particles with diameters less than 300 nm would include most, if not all, of these particles. This background suggests that an improved particulate monitor that measures the mass and surface concentrations of both PM2.5 and PM0.3 could provide the most relevant information on the effects of particulate matter on adverse health problems and that such a monitor would include both ultrafine particles and LDSA. Most inexpensive particle monitors currently available in the market use optical scattering techniques to measure particle concentrations and are limited to particles larger than 350 nm. Monitors that can detect particles smaller than 350 nm can become relatively expensive ($7000 to $16,000). The sensor to be developed within this project is an optical sensor that utilizes multiple angles and/or multiple wavelengths, scattering theory and advanced signal processing techniques to infer particle size information. This technology can be used in residential, commercial, and industrial applications or metropolitan environments to provide key insights into air quality and how it can impact human health. Because the monitor will be easy to use and interpret, compared to expensive reference instruments, information can be provided directly to the users so that they can be driven to action. In particular, low-income communities that are often impacted by poor air quality can more affordably determine real-time ambient conditions and drive positive change by using the monitor to identify pollution sources, appropriate mitigation measures, and then track the efficiency of these measures.
