Decades of land use change and its impact on air quality in Egypt’s Middle Nile Delta observed from space

Air pollution has become one of the most pressing environmental challenges globally, with significant consequences for public health and ecosystems. Recently, Gharbia Governorate has undergone remarkable changes in land use/land cover (LULC), leading to a variety of environmental impacts. These transformations have raised concerns about their potential influence on air quality, making it crucial to investigate how shifts in LULC are affecting pollution levels in the region. Understanding this relationship is vital for developing sustainable land management strategies and improving air quality monitoring in the area. This study aims to employ remotely sensed data integrated with Geographic Information System (GIS) to monitor the LULC changes and evaluate their influences on the governorate's air quality. Two Landsat 8 Operational Land Imager data, as OLI acquired in 2023, 2013, and Landsat 5 Thematic Mapper data, as TM 5 acquired in 2003, were used. A maximum likelihood classifier was used to produce a land cover map and track changes in land cover of the study area. Aqua, Terra, and Sentinel-5P were employed to measure the PM_2.5, CO, NO_2, and SO₂ concentrations. The classification results identified two dominant LULC classes: cultivated land and urban area. Between 2003 and 2023, urban areas increased by 136.2 km², while cultivated lands declined by 135.94 km², reflecting significant urban expansion. This land conversion was associated with a marked impact on air quality. PM_2.5 concentrations ranged between 7.12 and 8.66 µg/m³ during the study period. Notably, NO₂ levels peaked during autumn (3.13 µg/m³), while elevated CO and SO₂ concentrations were observed in summer (946.79 µg/m³) and winter (8 µg/m³), respectively. The highest pollutant levels were consistently recorded in the recently expanded urban areas compared to other land use categories. These findings demonstrate that urban sprawl has a significant and direct impact on air quality, highlighting the need for integrated land-use planning and air pollution control. The generated data provides a valuable foundation for sustainable development and environmental decision-making in Gharbia Governorate.