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Anshun is a prefecture-level city in southwestern Guizhou province, situated in the heart of China's karst landscape region. Positioned at approximately 1,100 meters above sea level on the Yunnan-Guizhou Plateau, the city occupies a strategic location along historical trade routes between Yunnan and central China. Anshun's urban core is nestled within a basin surrounded by limestone hills and mountains, creating a semi-enclosed topography that significantly influences local air circulation patterns. The city lies approximately 90 kilometers southwest of Guizhou's capital, Guiyang, within an agricultural transition zone where rural farming communities gradually give way to urban development. While not part of China's major industrial belts, Anshun has developed light manufacturing and food processing industries alongside its traditional agricultural economy. The city's proximity to the Huangguoshu Waterfall and numerous rivers, including tributaries of the Wujiang River system, provides some natural ventilation but the surrounding karst formations often trap pollutants within the basin. The urban-rural gradient shows decreasing pollution levels moving outward from the city center toward the surrounding countryside, though agricultural burning can occasionally affect regional air quality. Anshun's elevation provides some natural advantage against ground-level pollution accumulation compared to lower-lying cities, but the basin topography creates occasional temperature inversions that trap emissions from transportation, residential heating, and local industry.

Anshun experiences distinct seasonal variations in air quality influenced by the East Asian monsoon system and local topography. During spring (March-May), increasing temperatures and occasional rainfall help disperse pollutants, though occasional temperature inversions in the basin can lead to short-term pollution accumulation, particularly during calm mornings. The summer monsoon (June-August) brings the cleanest air conditions as prevailing southeasterly winds from the South China Sea sweep through the region, with frequent rainfall effectively scrubbing particulate matter from the atmosphere—this period offers optimal conditions for outdoor activities. Autumn (September-November) sees gradually deteriorating air quality as monsoon winds retreat and atmospheric stability increases, with October and November often experiencing the year's first significant pollution episodes due to reduced ventilation and occasional agricultural burning in surrounding areas. Winter (December-February) presents the most challenging conditions as temperature inversions become frequent in the basin, trapping emissions from residential heating (primarily coal and biomass) and vehicular sources—January typically shows the poorest air quality. Sensitive groups including children, elderly residents, and those with respiratory conditions should limit prolonged outdoor exposure during winter mornings and periods of atmospheric stagnation, while summer provides the safest window for outdoor exercise and activities.