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Guankou, situated in Hunan Province's central-eastern region, occupies a strategic position within China's Yangtze River Basin urban corridor. The city lies at approximately 28.1637°N latitude and 113.6433°E longitude, placing it in the Xiangjiang River valley with an elevation averaging 50-100 meters above sea level. This lowland basin location creates a natural topographic bowl that traps air pollutants, particularly during stable atmospheric conditions. Guankou's urban character blends industrial zones with residential districts, surrounded by agricultural plains that transition to forested hills in the distance. The Xiangjiang River flows nearby, providing some atmospheric moisture but insufficient to consistently disperse pollutants. Positioned within Hunan's industrial belt, Guankou experiences emissions from manufacturing, transportation, and residential heating that interact with regional agricultural burning. The urban-rural gradient shows decreasing pollution toward peripheral agricultural areas, though regional haze often blankets the entire basin. Proximity to Changsha metropolitan area contributes to transboundary pollution transport, while the surrounding hills limit ventilation except during strong northerly winds. This geographic configuration makes Guankou particularly vulnerable to particulate matter accumulation, especially PM2.5, which frequently exceeds health guidelines during unfavorable meteorological periods.

Guankou's air quality follows distinct seasonal patterns shaped by East Asian monsoons and local meteorology. Winter (December-February) brings the worst pollution as cold, stable air creates temperature inversions that trap emissions from heating and industry, with January typically experiencing peak particulate concentrations. Sensitive groups should minimize outdoor activities during these months, particularly on calm, foggy mornings. Spring (March-May) sees gradual improvement as increasing temperatures and occasional rainfall help disperse pollutants, though March can still experience poor air quality from lingering winter conditions and occasional dust transport. Summer (June-August) offers the cleanest air with the southeast monsoon bringing cleaner oceanic air, frequent rainfall scrubbing the atmosphere, and convective mixing preventing pollutant accumulation—ideal for outdoor activities. Autumn (September-November) begins with relatively good air quality in September but deteriorates through November as monsoon winds shift, atmospheric stability increases, and agricultural burning contributes to regional haze. Throughout the year, wind direction significantly impacts daily air quality, with northerly winds sometimes bringing cleaner air while southerly flows may transport pollution from adjacent industrial areas. Fog and high humidity can exacerbate pollution episodes by promoting secondary aerosol formation.