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Nestled in the Lhasa River Valley at an extraordinary elevation of 3,656 meters (11,995 feet), Lhasa stands as one of the world's highest cities, its geography fundamentally shaping its air quality dynamics. The city is encircled by the formidable Nyenchen Tanglha Mountains to the north and the Gangdise Mountains to the south, creating a natural basin that traps atmospheric pollutants. This topographic bowl effect, combined with the thin air of the Tibetan Plateau, means that emissions from urban activities—primarily vehicle exhaust, construction dust, and residential heating—accumulate rather than disperse efficiently. Lhasa lacks major industrial belts or dense agricultural zones in its immediate vicinity; pollution sources are predominantly localised within the urban core, with a sharp urban–rural gradient as one moves into the sparsely populated high-altitude grasslands. The Lhasa River flows through the city, but its modest size offers minimal moderating influence on air quality. Proximity to the Himalayas influences wind patterns, but the city's position in East Asia, far from the industrial heartlands of eastern China, means it does not experience significant transboundary pollution. The high elevation intensifies solar radiation, which can exacerbate photochemical reactions, though overall pollutant levels remain lower than in lowland Chinese megacities due to limited industrialisation.

Lhasa's air quality follows a distinct seasonal rhythm driven by its high-altitude continental climate and monsoon influences. In winter (December to February), pollution typically peaks due to temperature inversions that trap cold air and pollutants in the valley, compounded by increased emissions from heating systems burning coal or biomass. Sensitive groups, such as those with respiratory conditions, should limit outdoor exertion during these months, especially in calm morning hours. Spring (March to May) sees gradual improvement as temperatures rise and winds increase, though dust storms from the arid plateau can occasionally elevate particulate levels. Summer (June to August) offers the cleanest air, with the Indian monsoon bringing moisture and ventilation that disperse pollutants; this is the optimal season for outdoor activities like hiking in the surrounding mountains. Autumn (September to November) transitions to drier conditions, with pollution beginning to accumulate again as winds diminish and heating resumes. Fog is rare due to low humidity, but temperature inversions become more frequent towards late autumn. Health guidance emphasises monitoring local air quality reports year-round, using air purifiers indoors during peak pollution periods, and scheduling outdoor activities for midday in colder months when inversion layers may temporarily lift.