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Cariré, nestled in the southern interior of Ceará state, Brazil, occupies a geographically significant position within the larger Sertão region. Located at approximately -3.9508° latitude and -40.4728° longitude, the city’s terrain is characterized by undulating plains and low hills, typical of the semi-arid landscape. The elevation averages around 600 meters above sea level, contributing to a generally drier climate. Cariré sits within the Jaguaribe River basin, though the river itself is not immediately adjacent to the urban area; its influence is felt through groundwater resources and occasional seasonal flooding in surrounding agricultural lands. The surrounding landscape is predominantly scrubland (caatinga biome), interspersed with small-scale farming plots cultivating drought-resistant crops like cassava and corn. This agricultural activity, while vital to the local economy, can contribute to localized dust and particulate matter, particularly during the dry season when soil erosion is heightened. The urban–rural gradient transitions relatively quickly, with the caatinga encroaching upon the city limits. There are no major industrial belts directly adjacent to Cariré; however, the city serves as a regional service center for surrounding agricultural communities, leading to vehicular traffic as a key factor in local air quality. The regional climate, dominated by a pronounced dry season and a shorter, less intense wet season, significantly impacts the dispersal of pollutants. The relatively flat terrain and prevailing wind patterns influence how pollutants are transported and diluted, often leading to stagnation during periods of low wind speed.

Cariré’s tropical climate dictates a distinct wet and dry seasonal cycle, profoundly influencing its air quality. The dry season, typically spanning from June to November, is characterized by intense solar radiation, high temperatures, and minimal rainfall. This period often sees a build-up of particulate matter due to increased dust from agricultural fields and unpaved roads, exacerbated by wind erosion. The lack of rainfall prevents natural cleansing of the atmosphere. Conversely, the wet season (December to May) brings relief, with sporadic but significant rainfall events that wash pollutants from the air. However, the onset of the wet season can initially see a rise in humidity, which can trap pollutants closer to the ground, particularly in the early weeks. Temperature inversions, though less frequent than in colder climates, can occasionally occur during the dry season, trapping pollutants in a layer near the surface. The prevailing winds, generally from the northeast, play a crucial role in dispersing pollutants, but their strength and consistency vary seasonally. During the dry months, particularly August and September, outdoor activities should be approached with caution, especially for children, the elderly, and individuals with respiratory conditions. The wet season offers a more favorable period for outdoor pursuits, though vigilance regarding potential pollen levels during the transition months is advisable. Maintaining well-ventilated indoor spaces and avoiding strenuous activity during peak heat and dust events are recommended year-round.