AAAR 36th Annual Conference October 16 - October 20, 2017 Raleigh Convention Center Raleigh, North Carolina, USA
Abstract View
Using a Low-Cost Electrochemical Wireless Sensor Network to Provide Spatiotemporal Measurements of Hazardous Gases in a Manufacturing Setting
CHRISTOPHER ZUIDEMA, Nima Afshar-Mohajer, Sinan Sousan, Geb Thomas, Thomas Peters, Kirsten Koehler, Johns Hopkins School of Public Health
Abstract Number: 527 Working Group: Instrumentation and Methods
Abstract Heavy industrial manufacturing facilities have complex profiles of hazardous air contaminants resulting from work processes, particularly welding and other metal work, which vary over space and time. Contaminants of specific interest in this setting include: particulate matter, carbon monoxide (CO) and oxidizing gases such as nitrogen dioxide (NO2) and ozone (O3); here, we focus on gases. We have designed, validated and deployed a wireless sensor network (WSN) constructed with Alphasense (Essex, UK) electrochemical sensors for CO (CO-B4) and oxidizing gases (OX-B421) in a manufacturing facility. These electrochemical sensors have a linear response, fast response time, and sensitivity in the ppm range. The sensors are small, relatively inexpensive ($100-$200), have low power requirements and are modular, permitting dense spatial deployment in our WSN and facilitating high-resolution temporospatial measurements. Each sensor node connects wirelessly with a central, online database in the facility. The sensor nodes integrate the manufacturer’s signal processing circuit with an open-source microprocessor. The nodes of the WSN were calibrated for a range of concentrations of occupational interest for application in the manufacturing facility. The CO sensors in our WSN demonstrate good linear response in the range of 1-12ppm (R2=0.998). The oxidizing gas sensor detects both NO2 and O3 but is incapable of discriminating between the two gases. The oxidizing gas sensors in our WSN were tested over the range of 0.2–2.0ppm NO2 and 25–100ppb O3 separately and also demonstrated highly linear responses (NO2: R2=0.996; O3: R2=0.978). In a preliminary deployment, the WSN measured CO in the range of 0–12ppm and oxidizing gases in the range of 0–100ppb with clear diurnal and weekly patterns and spatial heterogeneity. Four pairs of co-located sensors also showed high measurement agreement (0.8996<R2<0.9976).