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

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 PM_1.0, PM_2.5, 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).