College of Geography and Ocean Sciences, Nanjing University, Nanjing 210023, China.
Institute of African Studies, Nanjing University, Nanjing 210023, China.
Int J Environ Res Public Health. 2021 Sep 6;18(17):9389. doi: 10.3390/ijerph18179389.
Africa's PM pollution has become a security hazard, but the understanding of the varying effects of urbanization on driven mechanisms of PM concentrations under the rapid urbanization remains largely insufficient. Compared with the direct impact, the spillover effect of urbanization on PM concentrations in adjacent regions was underestimated. Urbanization is highly multi-dimensional phenomenon and previous studies have rarely distinguished the different driving influence and interactions of multi-dimensional urbanization on PM concentrations in Africa. This study combined grid and administrative units to explore the spatio-temporal change, spatial dependence patterns, and evolution trend of PM concentrations and multi-dimensional urbanization in Africa. The differential influence and interaction effects of multi-dimensional urbanization on PM concentrations under Africa's rapid urbanization was further analyzed. The results show that the positive spatial dependence of PM concentrations gradually increased over the study period 2000-2018. The areas with PM concentrations exceeding 35 μg/m increased by 2.2%, and 36.78% of the African continent had an increasing trend in Theil-Sen index. Urbanization was found to be the main driving factor causing PM concentrations changes, and economic urbanization had a stronger influence on air quality than land urbanization or population urbanization. Compared with the direct effect, the spillover effect of urbanization on PM concentrations in two adjacent regions was stronger, particularly in terms of economic urbanization. The spatial distribution of PM concentrations resulted from the interaction of multi-dimensional urbanization. The interaction of urbanization of any two different dimensions exhibited a nonlinear enhancement effect on PM concentrations. Given the differential impact of multi-dimensional urbanization on PM concentrations inside and outside the region, this research provides support for the cross-regional joint control strategies of air pollution in Africa. The findings also indicate that PM pollution control should not only focus on urban economic development strategies but should be an optimized integration of multiple mitigation strategies, such as improving residents' lifestyles, optimizing land spatial structure, and upgrading the industrial structure.
非洲的 PM 污染已成为安全隐患，但人们对城市化在快速城市化背景下对 PM 浓度驱动机制的不同影响的理解还远远不够。与直接影响相比，城市化对相邻地区 PM 浓度的溢出效应被低估了。城市化是一个高度多维的现象，以前的研究很少区分城市化的多维驱动影响和相互作用对非洲 PM 浓度的影响。本研究结合网格和行政区单元，探讨了非洲 PM 浓度和多维城市化的时空变化、空间依赖模式和演变趋势。进一步分析了非洲快速城市化下多维城市化对 PM 浓度的差异影响和相互作用效应。结果表明，2000-2018 年期间，PM 浓度的正空间依赖关系逐渐增强。PM 浓度超过 35μg/m 的区域增加了 2.2%，非洲大陆 36.78%的地区 Theil-Sen 指数呈上升趋势。城市化是导致 PM 浓度变化的主要驱动因素，经济城市化对空气质量的影响强于土地城市化或人口城市化。与直接效应相比，城市化对两个相邻地区 PM 浓度的溢出效应更强，特别是在经济城市化方面。PM 浓度的空间分布是由多维城市化的相互作用产生的。任何两个不同维度的城市化相互作用对 PM 浓度都表现出非线性增强效应。鉴于多维城市化对区域内外 PM 浓度的不同影响，本研究为非洲跨区域联合控制空气污染策略提供了支持。研究结果还表明，PM 污染控制不仅应关注城市经济发展战略，还应优化整合多种缓解策略，如改善居民生活方式、优化土地空间结构和升级产业结构。
