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Nestled in the heart of Sierra Leone’s Eastern Province, Kenema serves as the nation’s third-largest city, functioning as a vital commercial hub situated within a landscape defined by rolling hills and dense tropical vegetation. Positioned at an elevation of approximately 140 meters above sea level, the city is enveloped by a mosaic of secondary forests and intensive agricultural zones, primarily dominated by cocoa and coffee plantations. This inland location, far from the cooling influence of the Atlantic coast, creates a distinct microclimate characterized by high humidity and relatively stable temperatures. The urban character of Kenema is defined by its rapid expansion along major transit corridors, where the urban-rural gradient is often blurred by encroaching smallholder farming practices. Geographically, the city sits within a basin-like depression, which significantly influences air quality by trapping localized emissions. The surrounding terrain, characterized by undulating plateaus, limits wind dispersion, particularly during the transition between the wet and dry seasons. Industrial activity remains largely artisanal, focused on small-scale mining support and agricultural processing, which contributes to localized particulate matter. However, the primary drivers of urban air quality are the dense traffic of motorcycle taxis and the widespread reliance on biomass fuel for domestic cooking. As the city continues to densify, the interaction between its topography and the regional wind patterns—specifically the influence of the Harmattan trade winds—becomes a critical factor in understanding the city’s atmospheric health and the movement of dust and smoke across this vibrant, landlocked tropical urban center.

Kenema experiences a distinct tropical climate governed by the alternation between the wet season and the dry season, both of which dictate the city’s atmospheric conditions. From May through October, the heavy monsoon rains provide a natural cleansing effect, scrubbing the atmosphere of particulate matter and reducing dust levels significantly. During these months, the air feels exceptionally fresh, and the lush surrounding vegetation acts as a biological filter. However, the true challenge to air quality arrives with the dry season, starting in November and peaking between December and February. During this period, the Harmattan winds blow from the Sahara, carrying vast quantities of fine dust particles across West Africa. In Kenema, these winds combine with local agricultural burning—a traditional method for land clearing before the planting cycle—leading to elevated levels of haze and smoke. Temperature inversions during early morning hours in the dry season further exacerbate the situation by trapping vehicle emissions and smoke near the ground level. Residents should exercise caution during these months, particularly in the early mornings when air quality is typically at its poorest. Sensitive groups, including those with chronic respiratory conditions or asthma, are encouraged to limit strenuous outdoor physical activity during the peak of the Harmattan when visibility is reduced and particulate matter is most concentrated. By March, the arrival of pre-monsoon showers begins to settle the dust, gradually improving air quality until the full onset of the rainy season, which remains the most favorable period for outdoor activity in Kenema.