Effects of common indoor air pollutants on the speed of sound

With growing concern for air quality in residential, commercial, and industrial settings, the need for inexpensive and reliable air quality sensors is growing. Since the speed of sound can be measured very precisely and reliably and the speed of sound of air is directly related to its chemical composition, measurement of the speed of sound can be used as a method to detect small changes in gas composition. The effects of small concentrations of fourteen common indoor air pollutants on the speed of sound of air are investigated. The deviations in the speed of sound from the pollutants at the maximum levels suggested by the World Health Organization (WHO), minimal risk levels developed by the Agency for Toxic Substances and Disease Registry (ATSDR), and the occupational safety levels developed by the National Institute for Occupational Safety and Health (NIOSH) are computed. The computations show that, at this time, a low cost acoustic resonant sensor is probably not sensitive enough to be used as an indoor...