Shen Huizhong, Tao Shu, Chen Yilin, Ciais Philippe, Güneralp Burak, Ru Muye, Zhong Qirui, Yun Xiao, Zhu Xi, Huang Tianbo, Tao Wei, Chen Yuanchen, Li Bengang, Wang Xilong, Liu Wenxin, Liu Junfeng, Zhao Shuqing
Laboratory for Earth Surface Processes, College of Urban and Environmental Sciences, Peking University, Beijing 100871, China.
Sino-French Institute for Earth System Science, College of Urban and Environmental Sciences, Peking University, Beijing 100871, China.
Sci Adv. 2017 Jul 19;3(7):e1700300. doi: 10.1126/sciadv.1700300. eCollection 2017 Jul.
Direct residential and transportation energy consumption (RTC) contributes significantly to ambient fine particulate matter with a diameter smaller than 2.5 μm (PM) in China. During massive rural-urban migration, population and pollutant emissions from RTC have evolved in terms of magnitude and geographic distribution, which was thought to worsen PM levels in cities but has not been quantitatively addressed. We quantify the temporal trends and spatial patterns of migration to cities and evaluate their associated pollutant emissions from RTC and subsequent health impact from 1980 to 2030. We show that, despite increased urban RTC emissions due to migration, the net effect of migration in China has been a reduction of PM exposure, primarily because of an unequal distribution of RTC energy mixes between urban and rural areas. After migration, people have switched to cleaner fuel types, which considerably lessened regional emissions. Consequently, the national average PM exposure concentration in 2010 was reduced by 3.9 μg/m (90% confidence interval, 3.0 to 5.4 μg/m) due to migration, corresponding to an annual reduction of 36,000 (19,000 to 47,000) premature deaths. This reduction was the result of an increase in deaths by 142,000 (78,000 to 181,000) due to migrants swarming into cities and decreases in deaths by 148,000 (76,000 to 194,000) and 29,000 (15,000 to 39,000) due to transitions to a cleaner energy mix and lower urban population densities, respectively. Locally, however, megacities such as Beijing and Shanghai experienced increases in PM exposure associated with migration because these cities received massive immigration, which has driven a large increase in local emissions.
在中国，直接的住宅和交通能源消耗（RTC）是导致环境中直径小于2.5微米的细颗粒物（PM）的重要因素。在大规模农村人口向城市迁移期间，RTC产生的人口和污染物排放量在规模和地理分布上都发生了变化，人们认为这会使城市中的PM水平恶化，但尚未进行定量分析。我们对向城市迁移的时间趋势和空间模式进行了量化，并评估了1980年至2030年期间其相关的RTC污染物排放以及对健康的后续影响。我们发现，尽管迁移导致城市RTC排放量增加，但在中国，迁移的净效应是减少了PM暴露，这主要是因为城乡之间RTC能源结构分布不均。迁移后，人们转向了更清洁的燃料类型，这大大减少了区域排放。因此，由于迁移，2010年全国平均PM暴露浓度降低了3.9微克/立方米（90%置信区间为3.0至5.4微克/立方米），相当于每年减少36,000例（19,000至47,000例）过早死亡。这种减少是由于移民涌入城市导致死亡人数增加142,000例（78,000至181,000例），以及分别因转向更清洁能源结构和城市人口密度降低导致死亡人数减少148,000例（76,000至194,000例）和29,000例（15,000至39,000例）的结果。然而，在当地，北京和上海等特大城市因迁移导致PM暴露增加，因为这些城市接收了大量移民，并推动了当地排放量的大幅增加。
