Applicability of compact and useful PM2.5 instrument with gas sensors in Japan and Thailand

Abstract

Sophisticated standard instruments are not always available for high-density multipoint air quality observations owing to their relatively high cost, large size, and high-power consumption. Low-cost sensors may be used as supportive or potential solutions for atmospheric observations. This study aimed to evaluate applicability of the compact and useful PM<inf>2.5</inf> instrument with gas sensors (CUPI-G), which can measure real-time temperature, humidity, particulate matter (PM<inf>2.5</inf>), carbon monoxide (CO), nitric oxide (NO), nitrogen dioxide (NO<inf>2</inf>), and oxidant, O<inf>x</inf> (O<inf>3</inf>+NO<inf>2</inf>), and to observe the respective air pollution patterns in the suburban areas of developed and developing countries, selected as Japan and Thailand, respectively. The CUPI-G was validated with collocated standard instruments at both sites using a mathematical correction method to improve reproducibility before observation. Air quality observations were conducted for two weeks respectively from June 1^st to June 14^th, 2022, in Kyoto City, Japan and from October 28^th to November 12^th, 2022, in Nong Khaem District, Bangkok Province, Thailand, using CUPI-G. In Japan, applicability of the CUPI-G revealed different correlations, r = −0.30 to 0.89 with data from the nearest air monitoring station. In Thailand, it achieved strong correlations, r = 0.71 to 0.82 with the results of the nearest station. This study revealed the applicability performance, aiding future deployment of the CUPI-G and corresponding air pollution characteristics at observatories. Our results suggest a better performance of CUPI-G at polluted sites and recommend its use in developing countries having less-developed sites with lack of routine measurement equipment.