Limoeiro do Ajuru, nestled in the state of Pará, Brazil, occupies a strategically important position within the Amazon biome. Located at approximately -1.8950° latitude and -49.3808° longitude, the city’s geography is dominated by undulating terrain characteristic of the Amazonian lowlands. The surrounding landscape is a tapestry of dense rainforest, interspersed with small rivers and streams, reflecting the region’s high rainfall and extensive river network. Elevation is relatively low, generally ranging from 100 to 250 meters above sea level, contributing to a humid, tropical climate. Limoeiro do Ajuru sits within a transitional zone, exhibiting a gradual urban–rural gradient as it expands outwards. While the city itself is a modest urban center with a population of around 29,569, it’s surrounded by agricultural lands, primarily focused on cattle ranching and small-scale farming, which can contribute to localized air quality concerns. The proximity to the Amazon River basin, though not directly on the main river, influences regional weather patterns and humidity levels. The city’s location within the Amazon also means it’s susceptible to the effects of deforestation and land clearing activities further afield, which can impact air quality through increased particulate matter and changes in regional atmospheric circulation. The lack of significant industrial belts within the immediate vicinity mitigates some pollution risks, but agricultural practices and biomass burning remain potential factors.

Limoeiro do Ajuru experiences a classic tropical climate, characterized by distinct wet and dry seasons rather than the four seasons found in temperate regions. The wet season, typically spanning from November to May, brings consistently high rainfall and humidity. During this period, air quality is generally impacted by increased moisture, which can trap pollutants closer to the ground, particularly during periods of reduced wind. Fog is also more common, further exacerbating this effect. The dry season, from June to October, sees a decrease in rainfall and a rise in temperatures. While lower humidity might seem beneficial, the dry conditions often lead to increased biomass burning for land clearing and agricultural purposes. This practice releases significant amounts of particulate matter and gases into the atmosphere, frequently resulting in periods of poorer air quality. The months of August and September are often the most challenging, coinciding with peak burning activity. Meteorological factors like wind patterns play a crucial role; stagnant air masses can trap pollutants, while stronger winds can disperse them. Sensitive groups, including children, the elderly, and individuals with respiratory conditions, should exercise caution during the dry season, particularly on days with visible smoke or haze. Limiting outdoor exertion and using air purifiers indoors can help mitigate exposure. During the wet season, while overall pollution levels may be lower, the increased humidity can still aggravate respiratory issues for some individuals.