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Chon Buri, the capital of Chon Buri Province in eastern Thailand, occupies a strategic position along the Gulf of Thailand's coastline, approximately 80 kilometers southeast of Bangkok. This coastal city sits at a low elevation, generally under 10 meters above sea level, with a gently undulating terrain that transitions from urban areas to surrounding hills and agricultural plains. Its geography profoundly influences air quality through multiple mechanisms. The city forms part of Thailand's Eastern Seaboard industrial corridor, one of the nation's most concentrated industrial zones, with heavy manufacturing, petrochemical complexes, and the massive Laem Chabang deep-sea port—Southeast Asia's largest—all contributing significant emissions. These industrial sources combine with dense urban traffic in Chon Buri's expanding metropolitan area, creating a persistent baseline of pollutants. The coastal location provides some natural ventilation from sea breezes, but this is often insufficient to disperse pollution effectively, especially when combined with the region's frequent temperature inversions that trap pollutants near the surface. Surrounding agricultural areas, particularly sugarcane fields, contribute seasonal burning emissions, while the urban-rural gradient sees construction dust and road particulates increasing as the city expands. The proximity to the Gulf of Thailand also introduces marine aerosols that can interact with industrial emissions, sometimes worsening particulate matter concentrations under specific meteorological conditions.

Chon Buri's tropical wet-and-dry climate creates distinct seasonal patterns in air quality, driven by monsoon shifts and meteorological conditions. During the dry season from November to April, particularly in the peak pollution months of January through March, air quality deteriorates significantly. This period experiences minimal rainfall, allowing pollutants from vehicles, industries, and agricultural burning to accumulate without washout. Northeast monsoon winds bring drier air from continental Asia, often carrying transboundary haze from regional biomass burning, while frequent temperature inversions trap pollutants close to the ground, especially during cool nights and mornings. Sensitive groups like children, elderly, and those with respiratory conditions should limit outdoor activities during these months, particularly in early mornings when inversion layers are strongest. The wet season from May to October brings improvement as southwest monsoon rains effectively scavenge pollutants from the atmosphere, though tropical storms can temporarily stir up dust before precipitation arrives. June through August typically offers the cleanest air for outdoor activities, despite high humidity. However, brief pollution spikes may occur during transitional periods in April-May and October-November when wind patterns shift and occasional stagnant conditions develop. Throughout the year, coastal fog can mix with industrial emissions to create reduced visibility and heightened health risks, requiring vulnerable residents to monitor local air quality reports regularly.