环境污染与城乡收入差距:作用机制与基于中国经济事实的检验

环境污染是与居民健康水平紧密相关的,并且会导致处于不同收入阶层的居民的健康人力资本投资决策呈现出异质性特征,从而影响居民收入差距。本文通过构建跨期经济模型研究环境污染对城乡收入差距的影响,研究发现:环境污染导致城镇居民和农村居民出现相同比例的健康损害,这种损害会拉大城乡居民绝对收入差距;处于低收入阶层的农村居民应对环境污染带来的健康损害会进行相对较少的健康人力资本投资,因而城乡居民的健康水平差异会逐渐拉大,所以城乡收入的相对差距也会随着环境污染的加剧而扩大。基于理论研究结果,运用中国2002—2013年的省级面板数据进行实证研究发现:(1)环境污染对中国城乡收入差距的影响显著为正,并且基于人均二氧化硫排放量和人均废水化学需氧量排放量的计量检验结果是一致的,这表明研究结论是稳健的;(2)运用门槛面板模型的计量结果表明当滞后一期的城乡收入差距增加到临界点之后,环境污染对城乡收入差距的正效应会明显增强,表明环境污染对处于不同收入阶层的城镇居民和农村居民的健康人力资本投资决策有显著的影响,环境污染进一步拉大城乡居民的相对收入差距;(3)本文的研究结果证明了在教育、政府行为、城镇化等影响城乡收入差距的核心因素之外,环境污染也是影响中国城乡居民收入差距的显著性因素,并且其影响会随着环境污染的加剧和期初收入差距的拉大而变得更加严重,因此在治理中国城乡收入差距的过程中,相关政策应该平衡环境污染成本在城镇居民和农村居民之间的分配。

Environmental pollution and the income gap between urban and rural residents: impacting mechanism and evidence from China's economic facts

Pollution is not only closely correlated with health stock,but also leads to different decisions of health investments of citizens at various income levels.As a result,the income gap between urban residents and rural residents could be affected by pollution.We develop an intertemporal economic model to study the impact of pollution and the urban-rural income gap.Our theory model proposes that pollution would enlarge the income gap between urban and rural residents in absolute values when residents are exposed to the same levels of pollution both in the rural and urban areas.It results in the greater extent to which pollution limits health investments by lowering health stocks among rural residents due to their lower initial income than the urban.Following our theoretical results,we seek for empirical evidence by using the China provincial data set over the period of 2000-2013.Our empirical results suggest the followings:① Pollution has a statistically significant and positive effect on the income gap between urban and rural residents.This conclusion is robust to different pollution measures,either the per capita emission of sulfur dioxide or the per capita emission of chemical oxygen demand in waste water.② The positive effect is even larger in the panel threshold model where the lag income gap hits the threshold.It indicates that the relative income gap widens more as rural residents' investment in health is more restricted by pollution.③ Along with the key factors of human capital accumulation,such as education,urbanization,and government behavior,pollution also contributes to the income gap.Its effect increases both in the pollution level and the initial income gap.Thus our results suggest making a balance between reducing the income gap between urban and rural residents and allocating the pollution by the health costs.