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Sirājganj, situated in Bangladesh's Rājshāhi Division along the Jamuna River's western bank, occupies a strategic position in the country's northern plains. This riverine city lies at approximately 24.4500°N, 89.7167°E, with an elevation averaging just 15-20 meters above sea level, characteristic of Bangladesh's low-lying deltaic terrain. The city's geography profoundly influences its air quality through multiple mechanisms. Sirājganj sits within the vast Brahmaputra River floodplain, surrounded by extensive agricultural lands where rice paddies and jute fields dominate the landscape. This agricultural belt contributes seasonal biomass burning emissions during post-harvest periods. The city's urban character blends traditional bazaars with growing commercial areas, creating an urban-rural gradient where pollution sources intensify toward the city center. Proximity to the Jamuna River provides some natural ventilation but also creates humidity that can trap pollutants. Sirājganj's location places it downstream from industrial zones in northern Bangladesh, with potential for transboundary pollution transport. The flat terrain offers little topographic relief to disperse pollutants, while the city's position within South Asia's Indo-Gangetic Plain makes it susceptible to regional haze episodes. Urban expansion has increased local emissions from transportation, construction, and household fuel use, interacting with the region's agricultural emissions to create complex pollution mixtures.

Sirājganj experiences distinct seasonal air quality patterns shaped by Bangladesh's monsoon climate. During winter (December-February), cool temperatures and frequent temperature inversions trap pollutants near the surface, creating persistent haze. Morning fog combines with emissions from heating sources and agricultural residue burning, making these months particularly challenging for air quality. Sensitive groups should limit morning outdoor activities during this period. Spring (March-May) brings rising temperatures and pre-monsoon dust storms that can temporarily worsen air quality, though increasing wind speeds generally improve dispersion. The summer monsoon (June-September) offers the cleanest air as heavy rains wash pollutants from the atmosphere and strong southwesterly winds provide excellent ventilation. This is the optimal season for outdoor activities. Autumn (October-November) sees deteriorating conditions as monsoon rains cease and agricultural burning increases during the post-Aman rice harvest. Calm winds and decreasing temperatures create conditions conducive to pollution accumulation. Throughout the year, humidity from the nearby Jamuna River can enhance secondary aerosol formation. Sensitive individuals should monitor local air quality reports year-round, use masks during peak pollution episodes, and plan outdoor activities for monsoon months when possible.