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Anyuan sits nestled within the complex topography of the Qinling-Daba mountain range in Gansu province, characterized by steep slopes and deep, narrow valleys. This high-altitude setting defines its urban character, as the town is constrained by the surrounding ridges, creating a compact settlement pattern where human activity is concentrated along the valley floor. Regionally, Anyuan serves as a transitional node between the rugged highlands and the more fertile agricultural basins of the south. The terrain is predominantly mountainous, with fragmented farmland clinging to the hillsides, which influences the local urban–rural gradient. This geography plays a critical role in air quality; the surrounding mountains act as physical barriers that inhibit the lateral dispersion of pollutants. When atmospheric stability occurs, the valley becomes a reservoir for particulate matter, effectively trapping emissions from domestic heating and local transport. While the area is far from the massive industrial belts of eastern China, the proximity to the Loess Plateau means it is susceptible to wind-borne mineral dust during the dry seasons. Proximity to small mountain streams provides some moisture, but the lack of large water bodies means there is minimal maritime moderation of the air. Consequently, the town's air quality is a direct product of its enclosure, where the interaction between steep topography and stagnant air masses often leads to localized pollution episodes, making the atmospheric chemistry highly dependent on the immediate valley microclimate. The resulting environment is one of isolated pockets of air that fluctuate based on altitude and slope orientation.

The air quality narrative in Anyuan follows a distinct seasonal cycle driven by the interplay of topography and meteorology. Spring is often the most challenging period, as the region is besieged by strong northwesterly winds carrying mineral dust from the Gobi Desert and the Loess Plateau. These dust storms spike particulate levels, making it a precarious time for those with respiratory sensitivities. As the season shifts into summer, the East Asian Monsoon brings increased humidity and frequent precipitation. This rainfall effectively scrubs the atmosphere, washing away particulates and leading to the cleanest air of the year, making June through August ideal for outdoor activity. Autumn brings a return to atmospheric stability; however, the cooling air often triggers subsidence inversions, where warm air traps pollutants near the valley floor. While generally pleasant, these periods of stagnation can cause pollutants to linger. Winter represents the peak of anthropogenic pollution, as the plummeting temperatures necessitate the widespread use of coal and biomass for domestic heating. Combined with frequent temperature inversions—where cold air settles in the valley and prevents vertical mixing—smog often blankets the town. Sensitive groups, including the elderly and children, should strictly limit outdoor exertion during December and January. Health guidance suggests utilizing indoor air filtration during these winter peaks and wearing protective masks during spring dust events. By understanding these cycles, residents can better navigate the seasonal shifts between the refreshing summer rains and the stagnant, smoke-filled winter troughs.