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Waikabubak, the capital of East Nusa Tenggara province in Indonesia, occupies a geographically significant position on the island of Sumba, a region characterized by a dramatic urban–rural gradient. Situated at approximately -9.6358° latitude and 119.4131° longitude, the city’s elevation averages around 200 meters above sea level, nestled within a landscape dominated by rolling hills and savanna grasslands. The surrounding terrain is largely undulating, transitioning quickly to steeper slopes further from the urban core, influencing local wind patterns and potential for pollutant dispersion. Sumba’s interior is a patchwork of traditional villages and extensive agricultural lands, primarily focused on dryland farming of corn, cassava, and coffee, with limited large-scale industrial activity in the immediate vicinity. The coastal location provides exposure to maritime influences, including sea breezes that can, at times, help to ventilate the city. However, the prevailing monsoon winds, coupled with the island’s topography, can also trap pollutants, particularly during drier periods. The urban character of Waikabubak is relatively modest, reflecting its smaller population of approximately 33,821. Development is concentrated around the main roads and market areas, with a gradual transition to more rural settlements and agricultural zones as one moves outwards. The lack of significant industrial belts minimizes direct industrial emissions, but agricultural practices and vehicle traffic contribute to localized air quality concerns. The island’s isolation and dependence on fossil fuels for power generation also play a role in the overall air quality profile.

Waikabubak experiences a distinct wet and dry season, profoundly impacting its air quality. The dry season, typically spanning from May to October, is characterized by lower rainfall and increased temperatures, leading to a build-up of pollutants. Reduced precipitation means fewer opportunities for atmospheric cleansing, while higher temperatures promote photochemical reactions that can exacerbate ground-level ozone formation. During this period, dust from agricultural activities, particularly land clearing and harvesting, becomes a significant contributor to particulate matter. The prevailing southeast monsoon winds, while generally bringing some ventilation, can also transport dust and smoke from distant agricultural fires across the island and even from neighboring islands, creating periods of hazy conditions. The wet season, from November to April, brings increased rainfall and higher humidity, naturally washing away pollutants and reducing dust levels. However, periods of persistent fog, particularly in the mornings, can trap moisture and pollutants close to the ground, creating localized pockets of reduced visibility and potentially elevated concentrations of certain pollutants. Months like July and August, within the dry season, often see the most challenging air quality conditions due to the combination of dry winds, agricultural activity, and potential for regional haze. Sensitive groups, including children, the elderly, and individuals with respiratory conditions, should limit prolonged outdoor exertion during these periods. During the wet season, while generally cleaner, those with allergies should be mindful of increased mold and pollen levels associated with higher humidity.