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Tlalnepantla de Baz occupies a strategic position within the densely urbanized Valley of Mexico, situated at approximately 2,250 meters (7,380 feet) above sea level in the State of México, immediately north of Mexico City. This elevation places it within the high-altitude Trans-Mexican Volcanic Belt, contributing to thinner air and reduced atmospheric mixing that can trap pollutants. The city lies on the former bed of Lake Texcoco, a now largely drained basin, with flat to gently undulating terrain that limits natural ventilation. Tlalnepantla is integral to the Mexico City Metropolitan Area, characterized by intense urbanization that merges with neighboring municipalities like Naucalpan and Ecatepec, creating a continuous urban fabric with minimal green buffers. Its location within the Valley of Mexico, surrounded by mountain ranges including the Sierra de Guadalupe to the northeast and the Ajusco-Chichinautzin range to the south, acts as a natural bowl that confines air masses, exacerbating pollution accumulation. Proximity to the heavily industrialized northern corridor of the metropolitan area, including manufacturing zones in Tultitlán and Cuautitlán Izcalli, introduces emissions from factories, warehouses, and transportation networks. While no major bodies of water remain nearby, historical hydrological patterns influence soil composition and dust generation. The urban–rural gradient is steep, with Tlalnepantla's core transitioning rapidly to peripheral industrial and residential sprawl, lacking significant agricultural zones to mitigate particulate matter. This geographic setting, combined with high population density and vehicular traffic, creates a challenging environment for air quality management, where topography and urbanization synergistically hinder pollutant dispersion.

In Tlalnepantla, air quality follows a distinct seasonal rhythm shaped by the subtropical highland climate and meteorological patterns of the Valley of Mexico. During the dry winter months from November to February, pollution typically peaks due to frequent temperature inversions that trap cold air near the surface beneath warmer layers, preventing vertical mixing of pollutants. Calm winds and reduced rainfall exacerbate this, leading to hazy conditions with elevated particulate matter and ozone precursors; sensitive groups like children, the elderly, and those with respiratory conditions should limit outdoor exertion, especially in December and January. Spring, from March to May, sees gradual improvement as increasing solar radiation and occasional winds aid dispersion, though late-season heat can spike ozone levels, making early mornings preferable for outdoor activities. The rainy summer monsoon from June to September brings relief, with afternoon thunderstorms and consistent winds from the east or southeast scrubbing the atmosphere, resulting in the cleanest air of the year—ideal for hiking in nearby natural areas like the Sierra de Guadalupe. Autumn, from October to November, marks a transition back to drier conditions, with pollution beginning to accumulate as rainfall diminishes and inversion events become more common; residents should monitor air quality forecasts during this period. Throughout the year, fog and smog episodes are common in cooler months, reducing visibility and compounding health risks. To mitigate exposure, plan strenuous activities for midday in summer or early morning in spring, and use air purifiers indoors during winter peaks.