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Bandar Seri Begawan, the capital of Brunei, occupies a distinctive geographical position on the northern coast of Borneo Island, nestled along the Brunei River near its confluence with the South China Sea. The city's urban character blends modern infrastructure with traditional water villages (Kampong Ayer), creating a unique urban-rural gradient where dense development transitions to mangrove forests and coastal wetlands. Situated in the Brunei-Muara District, the city lies at low elevation, generally below 50 meters, with flat terrain that extends inland towards gently rolling hills. This topography, combined with proximity to the sea, influences local air circulation patterns, often trapping pollutants when winds are calm. The city's location places it within Brunei's primary industrial belt, concentrated along the coast and riverbanks, where oil and gas facilities, power plants, and port operations contribute significantly to emissions. Additionally, its position in Southeast Asia exposes it to transboundary haze from agricultural burning in neighboring Kalimantan, Indonesia, particularly during dry seasons. The surrounding landscape—comprising tropical rainforests, agricultural zones, and marine environments—interacts with urban emissions, while the humid subtropical climate fosters conditions conducive to pollutant accumulation. The city's coastal setting moderates temperatures but also introduces marine vessel emissions, creating a complex air quality dynamic shaped by both local industry and regional atmospheric transport.

Bandar Seri Begawan experiences distinct seasonal variations in air quality, driven by monsoon patterns and regional climatic factors. During the northeast monsoon from December to March, increased rainfall and stronger winds from the South China Sea help disperse pollutants, resulting in relatively cleaner air, making this period favourable for outdoor activities. As the inter-monsoon period arrives in April and May, lighter winds and higher temperatures can lead to occasional haze buildup, though conditions generally remain moderate. The peak pollution months of August, September, and October coincide with the southwest monsoon and dry season, when reduced precipitation and prevailing winds from the south transport transboundary haze from Kalimantan, significantly degrading air quality. During these months, temperature inversions and stagnant air masses trap local emissions from vehicles, industry, and road dust, exacerbating pollution levels. Sensitive groups, such as children, the elderly, and those with respiratory conditions, should limit outdoor exposure during peak periods and monitor local air quality advisories. The transition to the northeast monsoon in November brings gradual improvement, with increasing rainfall scrubbing the atmosphere. Year-round, morning fog can occasionally intensify pollutant concentrations, highlighting the need for awareness of daily weather patterns when planning activities.