Five years after China announced an action plan to clean the country’s skies of pollution, levels of pollution in China have changed drastically. Through a number of policy measures, the Chinese government was able to impose restrictions on factory owners around the country to curb their contribution to polluting China’s skies. Despite succeeding in reducing the overall amount of pollution in China, a new paper claims that pollution in some parts of China has actually been on the rise.

In a paper conducted by the Massachusetts Institute for Technology (MIT), researchers found that China’s anti-pollution laws, that came as part of the country’s 2013 action plan, have indeed helped reduce the amount of sulfur dioxide in China’s air as early as 2014. As a result of the policies in place, the overall levels of sulfur dioxide have decreased by 13.9 percent.

Despite the decrease, however, researchers with MIT have pointed out that some regions in China have been complying with the anti-pollution policies more than others. Valerie Karplus, assistant professor at MIT and co-author of the paper, said that ‘key regions’ – or areas of China that are more densely populated and more heavily polluted, haven’t been performing as well as others.

“We see the lowest correspondence between sulfur dioxide reported by plants and in independent satellite measures in key regions,” Karplus said. These ‘key regions’ are namely Beijing and Shanghai, two of the more populated and, thus, polluted cities China. This, however, does not hold for every type of air pollution in China. According to statistics, levels of PM 2.5 have fallen by 20.8 percent in 2017 alone. 

Researchers found that power plants in ‘non-key regions’ complied with the decrease in the concentration of sulfur dioxide from 400 milligrams per cubic meter to 200 milligrams to cubic meter. In key-region areas, however, research found that power plants did not comply to the 50 milligrams per cubic meter limit.

Measurements of the decrease in pollution in China was based on a mixed method approach by which researchers compared power plant-based Continuous Emissions Monitoring Systems (CEMS) and satellite data from NASA. Using this method, researchers looked at more than 250 power plants across four regions of China and compared data to locate exactly where emission levels were exceeding the legal limits. The researchers were also adamant on ensuring the data they were using could not be easily manipulated by plant owners so as to yield accurate results.

Data provided by the CEMS, unfortunately, could be easily manipulated in favor of plant owners. The satellite data on the other hand, was not so easily manipulated, which is why the team opted for a mixed method approach to their research.

“Environmental policy doesn’t exist in a vacuum,” Karplus says. “It requires reshaping prevailing understanding of firms’ environmental responsibility and establishing credible reporting systems. And although China’s attempts to purify its air through bike-share, air purifiers, and building eco-friendly cities across the country, it seems the Asian superpower has a long way to go to completely cleanse its air of toxins.