Mulanay, Quezon, Philippines, occupies a strategically important position on the eastern coast of Luzon Island, nestled within the Bicol Region. Its coordinates (13.5222, 122.4042) place it within a predominantly mountainous terrain, characterized by steep slopes and valleys carved by numerous rivers and streams flowing towards the Pacific Ocean. The town’s elevation varies considerably, ranging from near sea level along the coastline to higher elevations inland, influencing local microclimates and air circulation patterns. The surrounding landscape is a mosaic of agricultural lands – primarily rice paddies and coconut plantations – interspersed with patches of secondary forests and remnant primary forest on the steeper slopes. This agricultural activity, while vital to the local economy, contributes to potential sources of particulate matter, particularly during burning seasons. Mulanay’s coastal location exposes it to maritime influences, including sea breezes that can disperse pollutants, but also to salt spray and potential impacts from distant industrial activity along the larger Luzon coastline. The urban–rural gradient is relatively sharp; the town center exhibits a moderate density of residential and commercial buildings, while the surrounding areas are predominantly rural, with small barangays scattered across the hillsides. The proximity to the Pacific Ocean and the prevailing wind patterns significantly impact the town’s air quality, often bringing in moisture and influencing the dispersion of pollutants released from both local and regional sources. The rugged terrain limits extensive industrial development, but agricultural practices and vehicle emissions remain key factors.

Mulanay’s tropical climate dictates a distinct wet and dry season, profoundly influencing its air quality. The dry season, typically spanning from November to May, often sees a slight increase in particulate matter concentrations. This is largely attributable to agricultural burning practices, where farmers clear fields for planting, releasing smoke and ash into the atmosphere. While sea breezes generally help disperse pollutants, periods of calm winds, particularly during the transition months (April-May), can lead to localized stagnation and a build-up of these particles. The wet season, from June to October, brings frequent rainfall and increased humidity, which naturally washes pollutants from the air, leading to improved air quality. However, intense rainfall events can also trigger landslides and flooding, potentially releasing dust and debris into the atmosphere. Fog, though infrequent, can occur during the cooler months (December-January), trapping pollutants near the ground and temporarily reducing visibility. Temperature inversions, where cooler air is trapped beneath warmer air, are less common but can occur during periods of prolonged calm weather, exacerbating pollution. Sensitive groups, such as children, the elderly, and individuals with respiratory conditions, should exercise caution during the dry season, particularly during periods of agricultural burning. Outdoor activities are generally more favorable during the wet season, although heavy rainfall can still pose challenges. Monitoring local weather forecasts and being aware of agricultural practices is crucial for making informed decisions about outdoor exposure.