Citation: Duangsuwan, S.; Prapruetdee, P.; Subongkod, M.; Klubsuwan, K. 3D AQI Mapping Data Assessment of Low-Altitude Drone Real-Time Air Pollution Monitoring. Drones 2022, 6, 191. https://doi.org/10.3390/ drones6080191 Academic Editors: Efstratios Stylianidis and Luis Javier Sánchez-Aparicio Received: 27 June 2022 Accepted: 26 July 2022 Published: 29 July 2022 Publisher’s Note: MDPI stays neutral with regard to jurisdictional claims in published maps and institutional affil- iations. Copyright: © 2022 by the authors. Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (https:// creativecommons.org/licenses/by/ 4.0/). drones Article 3D AQI Mapping Data Assessment of Low-Altitude Drone Real-Time Air Pollution Monitoring Sarun Duangsuwan 1, * , Phoowadon Prapruetdee 1 , Mallika Subongkod 2 and Katanyoo Klubsuwan 3 1 Electrical Engineering, Department of Engineering, King Mongkut’s Institute of Technology Ladkrabang, Prince of Chumphon Campus, Chumphon 86160, Thailand; phoowadon.pr@kmitl.ac.th 2 Business Administration, Department of Business Administration, King Mongkut’s Institute of Technology Ladkrabang, Prince of Chumphon Campus, Chumphon 86160, Thailand; mallika.su@kmitl.ac.th 3 Smart City Thailand Association (SCTA), Bangkok 10230, Thailand; katanyoo@eideas.co.th * Correspondence: sarun.du@kmitl.ac.th; Tel.: +66-99-1864411 Abstract: Air pollution primarily originates from substances that are directly emitted from natural or anthropogenic processes, such as carbon monoxide (CO) gas emitted in vehicle exhaust or sulfur dioxide (SO 2 ) released from factories. However, a major air pollution problem is particulate matter (PM), which is an adverse effect of wildfires and open burning. Application tools for air pollution monitoring in risk areas using real-time monitoring with drones have emerged. A new air quality index (AQI) for monitoring and display, such as three-dimensional (3D) mapping based on data assessment, is essential for timely environmental surveying. The objective of this paper is to present a 3D AQI mapping data assessment using a hybrid model based on a machine-learning method for drone real-time air pollution monitoring (Dr-TAPM). Dr-TAPM was designed by equipping drones with multi-environmental sensors for carbon monoxide (CO), ozone (O 3 ), nitrogen dioxide (NO 2 ), particulate matter (PM 2.5,10 ), and sulfur dioxide (SO 2 ), with data pre- and post-processing with the hybrid model. The hybrid model for data assessment was proposed using backpropagation neural network (BPNN) and convolutional neural network (CNN) algorithms. Experimentally, we considered a case study detecting smoke emissions from an open burning scenario. As a result, PM 2.5,10 and CO were detected as air pollutants from open burning. 3D AQI map locations were shown and the validation learning rates were apparent, as the accuracy of predicted AQI data assessment was 98%. Keywords: 3D AQI mapping; BPNN–CNN model; smoke detection; open burning; Dr-TAPM; data assessment 1. Introduction Open burning is the burning of unwanted materials such as waste, tree branches, leaves, grass, and plastics; through open burning, smoke and emissions are released directly into the air. During open burning, air pollutants are the main considerations for health, human life, society, and cities. Globally, 5.4 million deaths were attributed to ambient air pollution in 2021. At 89.0%, low and middle-income countries had the highest portion of deaths. In a regional breakdown, it was found that the southeast Asian regions accounted for 943,000 deaths, while the highest number of deaths was 1,254,000 for the western Pacific region [1]. In Thailand, open burning is a major cause of air pollution, resulting in numerous public health problems and even death. It is a source of haze smoke in northern Thailand. Most open burning is caused by activities such as agricultural management, forest foraging, waste burning, and combustion. During the summer session from January to April, a high air quality index (AQI) above 300 is typically reported every year, meaning it is dangerous for human health. Smoke from the open burning of fields is a leading cause of the smog Drones 2022, 6, 191. https://doi.org/10.3390/drones6080191 https://www.mdpi.com/journal/drones