Effects of urban renewal on green space: Evidence from airborne particulate matter in a mega city cluster

The increasing amount of skyscrapers in modern cities may modify the relationship between green space and regional air quality. To test that, here we study three decades of changes in air quality and urban renewal, including building composition and green space, in one of the largest and most rapidly -changing megacity clusters in China - the Pearl River Delta city cluster. Our results show that this region underwent substantial urban renewal, where more than 75% of all buildings were constructed over the past 30 years, and similar to 25% of all buildings emerged within the last 10 years. We analyze the spatial -temporal dynamics of airborne particulate matter across the entire region, and compare it to patterns of regional urbanization. We find that increases in the number of buildings exacerbate air pollution, especially during winter. Although our results also suggest that green space helps improve regional air quality, its efficiency diminishes with increasing building age. Collectively, our findings offer new insights into the complex relationship between air quality and urban development, with potentially important management implications, considering that the world's population is predicted to continue to grow in the coming decades.