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Silago, Southern Leyte, Philippines, occupies a dramatic and geographically complex coastal setting. Nestled along the eastern coast of the island of Leyte, it’s characterized by steep, rugged terrain rising sharply from the Philippine Sea. The municipality’s name derives from the Tagalog word ‘silong,’ meaning ‘under,’ referencing its location in the shadow of the towering mountains that dominate the landscape. This mountainous terrain significantly influences Silago’s air quality. The town is situated within a narrow coastal plain, bordered by the sea to the east and the rugged Sierra Madre mountain range to the west. Elevation varies considerably, ranging from sea level along the coast to over 800 meters in the interior highlands. This creates localized microclimates and influences wind patterns, often trapping pollutants in valleys during periods of low wind. The surrounding landscape is a mix of dense tropical rainforest and agricultural land, primarily dedicated to coconut and rice cultivation. While large-scale industrial activity is minimal, small-scale farming practices, including burning of agricultural waste, can contribute to localized air pollution events. The urban–rural gradient is relatively sharp; Silago town proper is a small, dispersed settlement, transitioning quickly to rural agricultural areas. The proximity to the Philippine Sea introduces a maritime influence, with sea breezes playing a role in dispersing pollutants, although the mountainous terrain can disrupt these patterns. The town’s location within a rain shadow area also impacts precipitation patterns, potentially exacerbating air quality issues during drier periods.

Silago’s tropical climate dictates a wet and dry season pattern, profoundly impacting its air quality. The dry season, typically from March to May, often sees a build-up of pollutants due to reduced rainfall and decreased wind speeds. The lack of consistent rainfall means fewer opportunities for atmospheric cleansing, and stagnant air conditions are more prevalent. Temperature inversions, where cooler air is trapped beneath warmer air, can occur during these months, further hindering vertical mixing and concentrating pollutants near ground level. Agricultural burning, a common practice for land clearing and waste disposal, intensifies during the dry season, releasing particulate matter and other harmful emissions. The wet season, from June to November, brings frequent rainfall and increased humidity, generally improving air quality by washing away pollutants and promoting better ventilation. However, intense storms can temporarily worsen air quality due to wind-blown dust and debris. December to February represents a transitional period with moderate rainfall and relatively stable conditions. Months like April and May are generally those to avoid for sensitive individuals, such as children, the elderly, and those with respiratory conditions, due to the potential for elevated particulate matter. During the wet season, while overall air quality improves, periods of heavy fog can reduce visibility and temporarily trap pollutants. Maintaining indoor air quality through proper ventilation and air filtration is crucial throughout the year, particularly during the dry season when outdoor air quality may be compromised.