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Zigong, situated in the Sichuan Basin of southwestern China, occupies a distinctive geographic position that profoundly influences its air quality dynamics. Nestled at coordinates 29.3390°N, 104.7790°E, this prefecture-level city lies approximately 200 kilometers southeast of Chengdu, the provincial capital, within the broader Yangtze River economic corridor. The urban area rests at an average elevation of 300-400 meters above sea level, positioned in a transitional zone between the basin's central plains and the surrounding low mountains and hills. Zigong's terrain is characterized by gentle slopes and river valleys, with the Tuo River flowing through the city, providing some natural ventilation but also creating microclimates that can trap pollutants. The city is surrounded by agricultural lands to the east and west, while industrial zones concentrate along transportation corridors, creating an urban–rural gradient where pollution sources intermix with residential areas. Zigong's location in the Sichuan Basin places it within a natural topographic bowl, surrounded by mountains on all sides—the Daba Mountains to the northeast, the Dalou Mountains to the south, and the Qionglai Mountains to the west—which significantly restricts atmospheric dispersion. This basin effect, combined with the city's position away from major coastal influences, means that pollutants from urban activities, including transportation, residential heating, and local industry (particularly salt and chemical production historically associated with the region), tend to accumulate rather than disperse readily. The proximity to the Tuo River and smaller tributaries creates humidity that can interact with emissions to form secondary pollutants, while the surrounding agricultural areas contribute occasional biomass burning during certain seasons. This geographic context creates a challenging environment for air quality management, where natural ventilation is limited and pollution tends to concentrate in the urban core.

Zigong's air quality follows a distinct seasonal pattern shaped by the interplay of basin topography and East Asian monsoon circulation. During winter (December-February), cold air masses settle in the Sichuan Basin, creating frequent temperature inversions that trap pollutants near the surface. This is compounded by increased residential heating emissions and calm winds, making January typically the most polluted period—sensitive groups should limit prolonged outdoor exposure during these months. Spring (March-May) brings transitional weather with occasional rainfall that helps cleanse the air, though biomass burning from surrounding agricultural areas can cause temporary spikes in particulate matter. The period from late March to April often sees improving conditions as monsoon winds begin to stir the stagnant air. Summer (June-August) experiences the East Asian summer monsoon, with southeasterly winds bringing moisture from the Pacific that enhances atmospheric mixing and precipitation, leading to the cleanest air of the year—June through August are generally favourable for outdoor activities. However, high humidity can combine with emissions to form ground-level ozone on hot, sunny days. Autumn (September-November) sees a gradual deterioration as monsoon winds retreat and atmospheric stability increases, with October and November often experiencing worsening conditions due to reduced dispersion and occasional agricultural burning. Throughout the year, fog is common in the basin, particularly in winter and autumn, which can interact with pollution to create haze episodes. Sensitive individuals should monitor daily conditions and consider indoor air purification during peak pollution seasons, while all residents benefit from planning vigorous outdoor activities for summer months when dispersion is optimal.