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Salvaterra de Magos, nestled in the Santarém district of Portugal, occupies a geographically significant position within the vast plains of the Ribatejo region. Located approximately 39.0253° N, -8.7933° W, the city’s terrain is predominantly flat, characteristic of the alluvial plains formed by the Tagus River. This flatness, while facilitating urban expansion, also presents challenges regarding air quality dispersion. The surrounding landscape is a mosaic of agricultural fields – primarily used for cereal cultivation and viticulture – interspersed with pockets of cork oak forests, a defining feature of the Portuguese landscape. The proximity to the Tagus River, Portugal’s longest river, influences local climate and humidity levels, potentially impacting pollutant behaviour. While Salvaterra de Magos isn't directly adjacent to major industrial belts, it lies within a region experiencing moderate agricultural activity, which can contribute to particulate matter emissions, particularly during harvest seasons. The urban–rural gradient is relatively gradual; the city seamlessly blends into the agricultural landscape, with smaller villages and rural settlements dotting the surrounding area. The elevation is low, averaging around 20 meters above sea level, further limiting vertical mixing of air pollutants. This low elevation, combined with the flat terrain, can exacerbate the effects of temperature inversions, trapping pollutants closer to the ground. The regional position, within a relatively open plain, means that prevailing winds are crucial in determining the city’s air quality, often carrying pollutants from distant sources.

Salvaterra de Magos experiences a Mediterranean climate, significantly influencing its air quality throughout the year. Spring (March-May) generally sees improved air quality as temperatures rise, promoting atmospheric mixing and dispersing pollutants. However, agricultural activities, including fertilizer application and pesticide spraying, can contribute to localized emissions. Summer (June-August) is typically the driest period, and while sunshine is abundant, stagnant air conditions can occasionally develop, particularly during heatwaves. These periods can lead to a build-up of pollutants, especially ozone, formed through photochemical reactions. Autumn (September-November) marks the beginning of harvest season, a period often associated with increased particulate matter from agricultural burning and machinery. The combination of cooler temperatures and calmer winds can trap these particles. Winter (December-February) often brings the most challenging air quality conditions. Temperature inversions, where a layer of warm air sits above cooler air near the ground, are more frequent, preventing vertical dispersion of pollutants. Fog, common during winter mornings, further exacerbates this issue by trapping pollutants close to the surface. Sensitive groups, including children, the elderly, and individuals with respiratory conditions, should limit outdoor activity during periods of stagnant air or fog, particularly in the mornings. During harvest season, residents should be mindful of potential smoke exposure and take necessary precautions. Overall, the months of November and December often present the most significant air quality concerns, while spring generally offers the most favourable conditions.