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Nestled in the fertile Sichuan Basin of southwestern China, Mianyang occupies a strategic position along the upper reaches of the Fu River, approximately 90 kilometres northeast of Chengdu. As Sichuan's second-largest city by population, it serves as a critical hub within the Chengdu-Chongqing Economic Circle, blending urban density with surrounding agricultural plains and forested hills. The city's terrain is predominantly flat to gently rolling, with an average elevation of around 500 metres above sea level, though it is flanked by the Longmen and Micang mountain ranges to the northwest and northeast, respectively. This basin topography significantly influences air quality by limiting natural ventilation; pollutants from urban activities—including vehicle emissions, construction dust, and residential heating—often become trapped under temperature inversions, particularly during calm winter months. The Fu River and its tributaries provide some local humidity but minimal dispersive effect. Mianyang's economy is driven by electronics manufacturing, defence industries, and scientific research, with industrial zones concentrated in its eastern and southern suburbs, while the western fringes transition into rice paddies and vegetable farms. This urban–rural gradient means that agricultural burning occasionally contributes to seasonal haze, though less so than in purely agrarian regions. Proximity to Chengdu also means transboundary pollution can drift in under prevailing westerly winds, compounding local emissions. The city's growth as a technology centre has intensified energy consumption and traffic, yet its location away from heavy coal belts moderates some industrial pollution compared to northern Chinese cities.

Mianyang's air quality follows a distinct seasonal rhythm shaped by the East Asian monsoon and basin meteorology. In winter (December to February), cold, stagnant air settles in the Sichuan Basin, fostering frequent temperature inversions that trap pollutants near the ground. Calm winds and high atmospheric pressure exacerbate this, making January and February the peak pollution months; sensitive groups like children, the elderly, and those with respiratory conditions should limit outdoor exertion during these periods. Spring (March to May) brings gradual improvement as warming temperatures increase vertical mixing, though occasional dust storms from the northwest can cause short-term spikes. By summer (June to August), the southwest monsoon ushers in humid air from the Indian Ocean, with increased rainfall and stronger winds effectively scavenging pollutants, making this the cleanest season for outdoor activities. However, high humidity can combine with emissions to form ground-level ozone on hot, sunny days. Autumn (September to November) sees a return to stable conditions as the monsoon retreats, with pollution levels rising again by late October, particularly under clear, calm skies that favour inversion layers. Fog is common in winter and early spring, often mixing with particulate matter to create dense smog. For health guidance, residents should monitor real-time air quality indices and plan vigorous exercise for summer mornings or after rainfall, while using air purifiers indoors during winter peaks.