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Tahuna, nestled on the northeastern peninsula of Sulawesi Utara (North Sulawesi) province, Indonesia, occupies a unique geographic position. Situated at coordinates 3.6119°S, 125.5008°E, the city is essentially an island within an island, being located on the Sangihe Islands archipelago. The terrain is predominantly volcanic, characterised by steep slopes and fertile valleys, rising to modest elevations. This volcanic origin contributes to the rich soil supporting local agriculture, primarily coconut plantations and clove farms. Tahuna’s urban character is that of a coastal town, heavily influenced by its proximity to the Pacific Ocean and the Celebes Sea. The surrounding landscape is a mix of dense tropical rainforest, coral reefs, and smaller, uninhabited islands. The urban-rural gradient is relatively sharp; the city centre quickly transitions into agricultural land and then dense forest. Air quality is significantly impacted by this coastal location. Sea breezes can disperse pollutants, but also carry moisture contributing to humidity and potential for haze from regional forest fires. The prevailing winds, influenced by the monsoon patterns, play a crucial role in pollutant transport. Limited industrial activity within Tahuna itself means that regional sources, including potential volcanic emissions and transboundary haze, are more significant contributors to air pollution than local industry.

Tahuna experiences a tropical climate, defined by distinct wet and dry seasons rather than traditional four seasons. The wet season, typically from September to May, brings increased rainfall and higher humidity. While rainfall can temporarily cleanse the air, the increased moisture also fosters mould growth and can trap pollutants near the ground, potentially worsening respiratory conditions. Air quality tends to be slightly better during the peak of the wet season due to the washing effect, but visibility can be reduced. The dry season, from June to August, is generally sunnier with lower humidity. However, this period coincides with increased risk of regional forest and peatland fires in neighbouring islands of Sulawesi and Kalimantan, leading to transboundary haze impacting Tahuna. These haze events are the primary cause of significant air quality deterioration. August is often the worst month for air quality. Temperature inversions, common during calmer periods, can exacerbate pollution by trapping pollutants. Sensitive groups – children, the elderly, and those with pre-existing respiratory conditions – should limit strenuous outdoor activity during haze events and the drier months. Monitoring wind direction is crucial; winds from the south and southwest are more likely to carry haze.