Xibeijie, situated in Gansu Province of northwestern China, occupies a strategic position along the ancient Silk Road corridor, approximately 1,500 meters above sea level on the eastern edge of the Hexi Corridor. This narrow passage between the Qilian Mountains to the south and the Gobi Desert to the north creates a distinctive urban-rural gradient where the city transitions abruptly from dense urban fabric to arid steppe and desert landscapes. The city's geography profoundly influences air quality through multiple mechanisms: its location in a rain-shadow region results in minimal precipitation to cleanse the atmosphere, while surrounding mountains trap pollutants during temperature inversions. Proximity to the Gobi Desert exposes Xibeijie to frequent dust storms, particularly during spring, which elevate particulate matter concentrations dramatically. The urban area itself, with over one million residents, generates typical urban pollution sources including vehicular emissions, residential heating, and small-scale industrial activities concentrated along the Jiuquan-Zhangye industrial belt. Limited water bodies in this arid region—with only seasonal rivers like the Heihe River providing minimal moisture—exacerbate dust suspension and reduce natural air purification. The city's position at the convergence of agricultural zones in the Hexi Corridor's oases and extensive pastoral lands creates a complex pollution mix of soil dust, agricultural burning residues, and urban emissions, all intensified by the region's continental climate with extreme temperature variations.

Xibeijie's air quality follows a distinct seasonal pattern shaped by its continental desert climate and regional meteorology. Spring (March-May) brings the most hazardous conditions as powerful winds from the Mongolian Plateau and Gobi Desert generate frequent dust storms, elevating PM10 and PM2.5 levels to their annual peaks; sensitive groups should avoid outdoor activities during these events, particularly in April when dust activity peaks. Summer (June-August) offers relatively cleaner air as increased convective activity and occasional rainfall from the East Asian monsoon's western fringe help disperse pollutants, though ozone levels may rise during hot, sunny afternoons. Autumn (September-November) sees deteriorating conditions as temperatures drop, heating systems activate, and stable atmospheric conditions develop, creating temperature inversions that trap pollutants near the surface, especially in October and November. Winter (December-February) presents the most complex scenario: bitterly cold temperatures drive intensive coal and biomass burning for heating, while persistent temperature inversions in the mountain-bounded corridor create prolonged pollution episodes; January typically experiences the worst urban pollution despite reduced dust activity. Sensitive individuals should monitor air quality forecasts year-round, use air purifiers indoors during pollution episodes, and schedule outdoor activities for summer mornings or autumn days following rainfall when dispersion conditions are most favorable.