The Evolution of Policy Instruments for Air Pollution Control in China: A Content Analysis of Policy Documents from 1973 to 2016

China's portfolio of air-pollution control policy instruments has gradually broadened since the 1970s from regulatory instruments to include numerous market-based and voluntary policy instruments. We demonstrate this broadened portfolio of policy instruments for air-pollution control with a computer-assisted content analysis of 148 central-level policy documents from 1973 to 2016. We identify 20 types of policy instruments in these documents, and analyze such things as their historical evolution, main subjects, frequency of use, and whether they were issued by a single agency or jointly with other agencies. Prior research has found several factors complicating the diversification of policy instruments in China, including the late start of coordinated governance of air pollution, overreliance on regulatory instruments, insufficient use of market-based and voluntary instruments, the high cost of collecting shared information on a web-based platform, and the choice of policy instruments resulting from the "campaign-style" of governance. Given such challenges, we expected the policy documents to show little diversification of policy instruments and little coordination among agencies. The content analysis results show, however, a gradual shift from a centralized, regulatory model to an increasingly coordinated model using a diverse portfolio of policy instruments.