Atlatlahucan, nestled in the state of Morelos, Mexico, occupies a geographically significant position within the central Mexican highlands. Located at approximately 18.9350° latitude and -98.9000° longitude, the city sits at an elevation of around 1,750 meters (5,742 feet) above sea level, contributing to a cooler climate compared to coastal regions. The surrounding landscape is characterized by a blend of volcanic terrain and fertile valleys, a legacy of the region's geological history. The Sierra de Chichinautzin mountain range looms to the east, influencing local wind patterns and creating potential for temperature inversions, a key factor in air quality. Atlatlahucan’s proximity to Mexico City, roughly 100 kilometers (62 miles) northwest, is a crucial element in understanding its air quality challenges. While not directly within the sprawling urban metropolis, it falls within the broader airshed, experiencing the impacts of distant industrial activity and vehicular emissions. The urban–rural gradient shifts rapidly around Atlatlalahucan; agricultural zones, particularly dedicated to maize and fruit cultivation, are prevalent in the immediate periphery, introducing biogenic volatile organic compounds (BVOCs) into the atmosphere. The Balsas River basin, though distant, influences regional weather patterns. The terrain’s undulating nature, combined with the mountain range, can trap pollutants, especially during periods of low wind speed. The city’s relatively small population (25,232) suggests a primarily rural character transitioning towards a more urbanized setting, with potential for localized pollution from small-scale industries and residential heating.

Atlatlahucan’s air quality exhibits a distinct seasonal pattern dictated by its subtropical highland climate. The dry season, typically spanning from November to April, often presents the most concerning air quality conditions. Reduced rainfall and lower humidity contribute to the formation of temperature inversions, where a layer of warm air traps cooler air (and pollutants) near the ground. This phenomenon is exacerbated by the surrounding mountains, which can impede atmospheric mixing. During these months, stagnant air conditions are common, leading to a build-up of particulate matter and other pollutants transported from Mexico City and surrounding industrial areas. The spring and summer months (May to October) bring the rainy season, characterized by increased precipitation and higher humidity. These conditions generally lead to improved air quality as rainfall washes pollutants from the atmosphere and increased humidity helps to bind particulate matter. However, periods of intense rainfall can also lead to flooding and the release of pollutants from contaminated sites. The transition months of April and October can be unpredictable, with periods of both improved and degraded air quality. During the cooler months, particularly December and January, residential wood burning for heating can contribute to localized pollution spikes. Sensitive groups, including children, the elderly, and individuals with respiratory conditions, should exercise caution during the dry season, limiting outdoor activities during periods of stagnant air and high humidity. Maintaining indoor air quality through proper ventilation and air filtration is also advisable.