The broader impact/commercial potential of this Small Business Innovation Research (SBIR) Phase I project is to improve health and save lives while addressing a market opportunity of over a billion dollars per year. Worldwide particulate matter air pollution is responsible for nearly as many deaths as cancer, and more than malaria and AIDS combined. The goal of the project is an inexpensive, consumer market air pollution sensor that offers performance comparable to laboratory instruments that cost hundreds to thousands of dollars. The proposed technology has important societal benefit as it will help mitigate the negative health effects of air pollution in the environment, home, and workplace. The proposed project contributes to scientific knowledge and understanding by investigating novel particulate matter analysis techniques and enabling a highly-sensitive, portable, and low-cost monitor for studies of air pollution. With the form-factor of a AA-battery, it is the only particulate matter air pollution sensor that can fit in devices like the Amazon Echo or Google Nest. Markets for the sensor include smart homes, smart cities, green buildings, automobile cabin monitoring, air purifiers, industrial hygiene, and others. The proposed project will investigate a novel sensor for monitoring particulate matter air pollution. Existing air pollution monitors are expensive, large, and power hungry. The monitors on the consumer market use optical techniques that provide only a proxy estimate of pollution levels and are unable to detect ultrafine particulates which have diameters smaller than 100 nanometers. These ultrafine particulates pose serious health risks. The sensor of this work employs thermophoretic deposition of airborne particulates from a sample stream onto an acoustic wave resonator, and determines the mass deposited by measuring the frequency shift of a sustaining electronic oscillator circuit. The monitor of this work detects particulates from a few microns in diameter to ultrafine, and provides a true mass concentration measurement of the pollution, which is acknowledged as the industry gold-standard. Key activities of the proposal include the development of innovative techniques to collect and analyze particulates and to improve the sensor stability and lifetime. Anticipated technical results include enhanced monitor longevity, improved level of detection, improved manufacturability, and a significant reduction in power consumption. Coupling the sensor to a cell-phone or other wireless device would enable dense temporal and spatial wireless air quality measurements.