An investigation of time-dependent ozone (O₃) concentration using Geographic Information System: a case study in Central of Bangkok, Thailand

Abstract The World Health Organization (WHO) estimates that approximately 7 million people die each year due to exposure to polluted air. Ground-level ozone is one of the air pollutants that forms as a result of chemical reactions, specifically through photochemical processes. This study utilized GIS to investigate the ozone concentration in 29 districts in Central Bangkok, Thailand, aiming to assess the health risks associated with ozone and compare them with standard values. According to this study, the ozone concentration in the Bangkok area is generally low during the time range of 01:00 - 08:00 and 17:00 - 00:00, while it tends to be high during the daytime (from 9:00 - 16:00). The highest ozone concentration exceeding the defined safe limit (> 100 ppb) for a short duration (1 hour) occurred in Pubpla during the study period. Additionally, some districts, namely Bang Na, Phra Khanong, Suan Luang, Bang Kapi, and Wang Thonglang, experienced ozone concentrations surpassing the average standard limit (>70 ppb) over an 8-hour period. The high ozone concentrations in these areas can be attributed to their dense population. The increased usage of motor vehicles and high temperatures during working hours contribute to the ease of ozone formation at the surface.