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Using Indoor Positioning and Mobile Sensing for Spatial Exposure and Environmental Characterizations: Pilot Demonstration of PM2.5 Mapping

Cheng, Kai-Chung, Tseng, Ching-Hao, Hildemann, Lynn M.
Environmental science & technology letters 2019 v.6 no.3 pp. 153-158
air, air quality, buildings, monitoring, particulates, photometers, portable equipment, smoke, walking
New indoor positioning technology makes it possible to use air measuring devices carried by occupants to characterize spatiotemporal patterns of exposure and air quality inside buildings. This pilot study investigated the potential of a mobile monitoring method to map highly variable PM2.5 distributions inside an occupied one-bedroom apartment, coupling a new ultrasound localization method with a pair of collocated research-grade and low-cost sensors (SidePak and PTQS). Measuring the position of the mobile sensing node every 1 s, down to the centimeter scale, this method generated detailed occupant moving trajectories and location histories on a floor plan map, allowing identification of microenvironments causing transient peak exposures. Utilizing a random walking approach throughout the apartment, it identified smoke intrusion sources and captured the spatial distributions of PM2.5 using interpolated two-dimensional concentration fields. The correlations between SidePak and PTQS were evaluated when they were used as portable devices for (i) occupant exposure and (ii) indoor environmental mapping applications. This new mobile sensing method is most effective with a rapidly responding air monitor (e.g., SidePak photometer).