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Kaunas, Lithuania's second-largest city, occupies a strategic position at the confluence of the Nemunas and Neris rivers in the central part of the country, approximately 100 kilometres west of the capital Vilnius. Situated within the Kaunas Basin, the city's terrain is characterised by gently rolling hills with an average elevation of 48 metres above sea level, though surrounding areas rise to over 100 metres, creating a subtle topographic bowl that can influence local atmospheric conditions. This urban centre serves as a crucial transportation hub connecting Baltic ports with Eastern European markets, positioned along the traditional industrial belt stretching from Klaipėda to Vilnius. The surrounding landscape transitions from dense urban fabric in the city centre to suburban developments, then to mixed agricultural zones and forested areas beyond the metropolitan boundary, creating distinct urban–rural gradients that affect pollution dispersion. Kaunas's location between two major rivers provides natural ventilation corridors, but the city's historical industrial heritage—including manufacturing, food processing, and energy production facilities concentrated along the river valleys—combined with modern transportation emissions creates persistent urban pollution sources. The proximity to the Kaunas Lagoon (reservoir) to the east and numerous smaller lakes in the region introduces moisture that can interact with pollutants, while the city's position in the continental climate zone means it experiences temperature inversions that trap emissions, particularly during calm winter periods when cold air settles in the river valleys.

Kaunas experiences distinct seasonal air quality patterns shaped by its continental climate and urban geography. During winter (December-February), pollution typically peaks due to increased residential heating emissions from wood and fossil fuels combined with frequent temperature inversions that trap pollutants in the river valleys, creating persistent haze; sensitive groups should limit prolonged outdoor exposure during calm, cold spells. Spring (March-May) brings gradual improvement as increased precipitation washes pollutants from the atmosphere and stronger winds enhance dispersion, though March can still experience poor air quality during transitional weather patterns. Summer (June-August) generally offers the cleanest air with active atmospheric mixing, longer daylight hours reducing artificial lighting needs, and decreased heating emissions, making this the optimal season for outdoor activities despite occasional ozone formation during heatwaves. Autumn (September-November) sees a gradual deterioration as temperatures drop and heating systems activate, with October-November particularly vulnerable to pollution accumulation during stable atmospheric conditions and reduced sunlight hours; sensitive individuals should monitor air quality forecasts as seasonal transitions occur. Throughout the year, wind patterns from the west and southwest typically bring cleaner marine air from the Baltic Sea, while easterly winds may transport regional agricultural or industrial emissions, with fog events most common in autumn and winter exacerbating pollution visibility and health impacts.