A lightweight low-cost and multipollutant sensor package for aerial observations of air pollutants in atmospheric boundary layer

Abstract

A lightweight low-cost multipollutant sensor package is particularly portable to aerial measurements and field campaign due to its light weight (2.0 kg), compact size (L × W × H, 22 × 15 × 10 cm), and low energy-consumption (20 Wa). The sensor system consists of electrochemical sensors measuring O3, NO2, NO, SO2, CO, an optical counting (OPC) particulate matter (PM) sensor for PM1.0, PM2.5, and PM10, a miniature photoionization detector (PID) for total volatile organic compounds (TVOCs), and metrological sensors for air temperature, relative humidity (RH) and air pressure. All sensor signals were collected and transferred by a data acquirement (DAQ) logger. The sensor data were saved in a microcomputer and transmitted wireless by a GSM/GPS module. All sensors and the accessories were integrated and installed in a thermal insulation foam package, of which temperature was stable at 25 °C to avoid the temperature effect. A silicone desiccant tube was connected to the inlet of air sample to minimize the RH influence. The sensor performances were compared with on-ground reference instruments for a 21-day field campaign and commercial portable instruments from Thermal Scientific and Vaisala in aerial observations. All gas sensors and PM sensor showed good correlations with the reference instruments with R2 varying from 0.81 to 0.93 and slope from 0.89 to 1.35. The O3 sensor performed best with R2 = 0.93 and slope = 1.02. In aerial measurements PM and O3 sensors obtained similar vertical profiles of PM and O3 with those obtained by commercial Thermal PTR PM monitor and Vaisala O3 sounding sensor, respectively. The sensor package was successfully deployed to observe the vertical profiles of air pollutants on a tethered balloon and to exactly locate exhaust sources in an industrial park with an unmanned aerial vehicle (UAV). Our sensor package was substantiated to be a reliable and accurate device for aerial measurements of air pollutants in atmospheric boundary layer (ABL).