Environmental problems have become an important factor causing the rich to leave China—but one academic has now suggested that they should first pay an environmental levy. Chen Guoen, a professor at Wuhan University, said that some Western investment-for-citizenship schemes are tempting China’s rich to emigrate and enjoy cleaner air. According to Chen, China should respond by imposing an environmental restoration levy on those leaving—their accumulation of wealth will have had environmental consequences, and they should not be allowed to take that money and run.

While some are migrating overseas, others are becoming internal migrants. Some members of the middle class, fed up with the crowding and air pollution of the big cities, are fleeing to smaller and less polluted cities like Dali in Yunnan province, Sanya on Hainan province, Weihai in Shandong province, or Zhuhai in Guangdong province.

Zhang Xiaode, head of the Chinese Academy of Governance’s Institute of Ecological Civilization, said that China’s smog problems are making people doubt the common view that urban life is preferable. In the next five to eight years, he thinks that China will see a reversal of urbanization, with city residents heading for rural areas.

Over the last year worsening environmental problems in China such as air pollution and food and water safety have become an important factor in people’s decisions to leave the country, according to The Global Talent Blue Book: Chinese International Migration 2014, recently published by the Social Sciences Academic Press. The report refers to a 2013 survey by New Fortune magazine, which found environmental and healthcare factors were the second most important consideration in emigration decisions, with almost seventy percent of respondents citing these as major reasons.

Wang Huiyao, editor of the report and director of the Center for China and Globalization think tank, describes the difference in numbers between those leaving and moving to China as an “emigration deficit.” He thinks air pollution is contributing to this deficit, and has called for China to set up an immigration bureau to attract global talent.