San Juan Air Quality Index (AQI)

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San Juan, nestled in the province of Southern Leyte, Philippines, occupies a geographically complex position. Located at 10.2700°N, 125.1800°E, the municipality is characterized by a rugged, mountainous terrain typical of the central Philippine archipelago. The city’s elevation contributes to unique microclimates and influences air circulation patterns. San Juan is not a large urban centre, with a population of approximately 14,912, representing a relatively strong urban-rural gradient. It’s situated inland, a short distance from the Bohol Sea, but shielded by the mountainous interior. This proximity to the sea introduces a constant supply of moisture, impacting local weather and potentially contributing to aerosol formation. The surrounding landscape is dominated by agricultural lands – primarily coconut plantations and rice paddies – alongside pockets of forested areas. While San Juan itself doesn’t host heavy industry, regional agricultural practices, including the burning of agricultural waste, can contribute to localized air pollution. The terrain funnels winds, creating areas of stagnation that can exacerbate pollutant concentrations, particularly during calm weather conditions. The city’s position within Leyte, a region prone to typhoons, also means that storm events can redistribute pollutants and impact air quality through increased dust and debris.

San Juan experiences a distinct wet and dry season, heavily influenced by the Philippine monsoon system. Air quality generally improves during the wet season (roughly November to May) as rainfall effectively washes particulate matter from the atmosphere. However, increased humidity can also promote the formation of secondary pollutants. The northeast monsoon, bringing cooler temperatures and consistent rainfall, typically results in the cleanest air, particularly from December to February. Conversely, the dry season (June to October) sees a noticeable decline in air quality. This is largely due to increased dust from agricultural activities, drier conditions facilitating the spread of wildfires, and reduced rainfall for natural cleansing. March and April are often the most challenging months for respiratory health. Temperature inversions, where a layer of warm air traps cooler air below, can occur during the transition periods between seasons, exacerbating pollution. Sensitive groups – children, the elderly, and those with pre-existing respiratory conditions – should limit strenuous outdoor activity during the dry season and be mindful of potential smoke from agricultural burning. Monitoring wind patterns is crucial, as shifts can quickly transport pollutants into the municipality.