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Marmande, nestled in the Nouvelle-Aquitaine region of southwestern France, occupies a geographically strategic position within the Lot-et-Garonne department. The city is situated on the banks of the Garonne River, a major waterway that influences local climate and air circulation patterns. The terrain is generally flat, characteristic of the Aquitaine Basin, with a low elevation averaging around 25 meters above sea level. This flatness can contribute to the trapping of pollutants during stable atmospheric conditions. Surrounding Marmande is a predominantly agricultural landscape, dominated by vineyards, plum orchards (for which the city is renowned), and arable farmland. While Marmande itself isn’t heavily industrialised, its proximity to larger industrial centres further downstream along the Garonne, such as Bordeaux, means it can experience the transport of pollutants. The urban-rural gradient is relatively sharp; moving just a few kilometres from the city centre quickly leads to open countryside. This proximity to agricultural land introduces potential sources of ammonia and particulate matter from farming activities, impacting local air quality. The Garonne acts as a corridor for air movement, but can also contribute to humidity and fog formation, potentially exacerbating pollution episodes. Understanding these geographical factors is crucial for assessing and mitigating air quality challenges in Marmande.

Marmande’s air quality follows a distinct seasonal pattern. Winter, from December to February, often sees the poorest air quality due to increased residential heating using wood and fossil fuels, coupled with temperature inversions that trap pollutants near the ground. Calm, stable weather conditions are frequent during these months, hindering dispersion. Spring (March-May) brings improvement as temperatures rise and wind speeds increase, diluting concentrations. However, agricultural activities intensify, potentially releasing ammonia from fertilizer application. Summer (June-August) generally offers the cleanest air, with strong convective currents and prevailing winds effectively dispersing pollutants. However, prolonged heatwaves can lead to increased ozone formation, a secondary pollutant. Autumn (September-November) is a transitional period. The return to heating systems begins to degrade air quality, and harvest activities can contribute to particulate matter. Fog, common in autumn mornings, can trap pollutants. Sensitive individuals – children, the elderly, and those with respiratory conditions – should limit strenuous outdoor activity during winter and autumn mornings. Monitoring pollen levels is also important in spring. Avoiding peak traffic hours and being mindful of agricultural practices can further reduce exposure.