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Roxas City, the capital of Capiz province in the Philippines, occupies a strategically important position on the southern coast of Panay Island. Its coordinates (11.5894° N, 122.7511° E) place it within a predominantly low-lying coastal plain, gently sloping towards the Visayan Sea. The city is bisected by the Roxas River, a vital waterway that historically facilitated trade and continues to influence local hydrology. The surrounding landscape is a mosaic of rice paddies, coconut plantations, and small-scale aquaculture farms, characteristic of the fertile Capiz River basin. This agricultural intensity, while economically significant, contributes to localized sources of air pollutants, particularly during burning seasons. Roxas City exhibits a clear urban–rural gradient; the city center boasts denser commercial and residential areas, while the periphery gradually transitions into agricultural lands and smaller barangays. Elevation is minimal, rarely exceeding 10 meters above sea level, which limits natural dispersion of pollutants and can exacerbate ground-level concentrations. The proximity to the Visayan Sea introduces a maritime influence, with sea breezes playing a role in ventilation, though this effect can be overridden by stagnant atmospheric conditions. There are no major industrial belts directly adjacent to Roxas City, but nearby municipalities may have smaller-scale processing facilities impacting regional air quality. The terrain’s flatness and coastal location combine to create a setting where localized emissions can linger, particularly during periods of reduced wind activity.

Roxas City experiences a tropical climate with distinct wet and dry seasons, significantly influencing its air quality profile. The dry season, typically from November to May, often sees a slight increase in particulate matter due to agricultural burning practices in the surrounding rice fields and coconut plantations. Farmers clearing land or preparing fields frequently employ controlled burns, releasing smoke and ash into the atmosphere. While these burns are often regulated, enforcement can be challenging, leading to temporary spikes in air pollution. The wet season, from June to October, brings monsoon rains and increased humidity, generally leading to improved air quality as precipitation washes away pollutants and higher humidity traps particulate matter. However, periods of prolonged rainfall can also lead to stagnant air and localized fog, particularly in low-lying areas near the river, which can trap pollutants. Temperature inversions, though less frequent than in temperate climates, can occasionally occur during the cooler months (December-February), trapping pollutants near the ground. Sea breezes, a consistent feature of Roxas City’s climate, usually provide some degree of ventilation, dispersing pollutants outwards. Sensitive groups, such as children, the elderly, and individuals with respiratory conditions, should be mindful of agricultural burning periods (typically January-March) and avoid prolonged outdoor exposure during these times. During the wet season, while overall air quality is generally better, periods of fog or stagnant air can still pose a risk, warranting caution and awareness of local conditions.