Pamplona, a small municipality nestled in the province of Cagayan, Philippines, occupies a geographically significant position within the sprawling Cagayan River Valley. Located at approximately 18.4661° N, 121.3425° E, the town sits at a modest elevation, contributing to a relatively mild climate. The surrounding landscape is dominated by fertile agricultural lands, a crucial component of the region's economy, primarily dedicated to rice cultivation and corn farming. This proximity to intensive agricultural zones introduces potential sources of air pollutants, including particulate matter from tilling and burning agricultural waste, though on a smaller scale than larger industrial areas. The Cagayan River, a major waterway, flows nearby, influencing local humidity and potentially dispersing pollutants under favourable wind conditions. Pamplona’s urban character is distinctly rural, with a low population density and limited industrial activity. The urban–rural gradient is gradual, transitioning seamlessly into the agricultural hinterland. The town’s location within a valley can, at times, exacerbate air quality issues, particularly during periods of temperature inversion where cooler air settles in the valley floor, trapping pollutants. The prevailing winds, generally easterly, play a crucial role in the dispersal of any emissions, though their effectiveness is dependent on atmospheric stability. The lack of major highways directly traversing Pamplona minimizes traffic-related pollution, a factor distinguishing it from larger urban centres. The overall geographic setting presents a mixed picture – agricultural activity introduces localized pollution, while the valley topography and prevailing winds can influence pollutant dispersion.

Pamplona’s tropical climate dictates a distinct wet and dry season, significantly impacting air quality patterns. The wet season, typically spanning from June to November, brings frequent rainfall and high humidity. While the rain naturally helps to cleanse the atmosphere by washing away particulate matter, the increased humidity can contribute to the formation of ground-level ozone, a respiratory irritant, particularly during periods of intense sunlight following rainfall. The dry season, from December to May, often sees clearer skies but also a greater risk of air quality degradation. During this period, agricultural burning, a common practice for land preparation, releases significant amounts of smoke and particulate matter into the air. Temperature inversions are more likely to occur during the cooler months (January-February), trapping pollutants close to the ground, especially in the valley setting. Fog, common during the dry season mornings, can also exacerbate the issue by reducing atmospheric mixing and concentrating pollutants. The months of April and May, coinciding with peak agricultural activity and drier conditions, are generally periods to exercise caution, particularly for individuals with respiratory sensitivities. Sensitive groups, including children, the elderly, and those with pre-existing respiratory conditions, should limit prolonged outdoor exposure during these times. During the wet season, while overall particulate matter may be lower, the potential for ozone formation warrants awareness, especially during sunny days following rainfall. Maintaining awareness of local weather patterns and agricultural practices is key to mitigating potential health risks associated with air quality fluctuations.