The distribution of income is worse than you think: Including pollution impacts into measures of income inequality

This paper calculates the distribution of an adjusted measure of income that deducts damages due to exposure to air pollution from reported market income in the United States from 2011 to 2014. The Gini coefficient for this measure of adjusted income is 0.682 in 2011, as compared to 0.482 for market income. By 2014, we estimate that the Gini for adjusted income fell to 0.646, while the market income Gini did not appreciably change. The inclusion of air pollution damage acts like a regressive tax: with air pollution, the bottom 20% of households lose roughly 10% of the share of income, while the top 20% of households gain 10%. We find that, unlike the case for market income, New England is not the most unequal division with respect to adjusted income. Further, the difference between adjusted income for white and Hispanics is smaller than expected. However, the gap in augmented income between whites and African-Americans is widening.

本研究针对2011至2014年美国的报告市场收入，扣除因暴露于空气污染所造成的损害后，测算调整后收入（adjusted income）的分布特征。该调整后收入的基尼系数（Gini Coefficient）在2011年为0.682，而同期市场收入（market income）的基尼系数仅为0.482。至2014年，经我们估算，调整后收入的基尼系数降至0.646，而市场收入的基尼系数未出现显著变化。纳入空气污染损害的核算相当于征收累退税（regressive tax）：受空气污染影响，收入最低的20%家庭的收入份额约缩减10%，而收入最高的20%家庭的收入份额则提升10%。研究发现，与市场收入的情形不同，以调整后收入衡量，新英格兰地区（New England）并非最不平等的分区。此外，白人与西班牙裔群体间的调整后收入差距小于预期。不过，白人与非裔美国人之间的调整后收入差距正在扩大。