Relationship between air quality and economic development in the provincial capital cities of China.

Air pollution in China has become increasingly severe with rapid economic growth in recent years. We analyzed the relationship between the gross regional product (GRP) per capita and the Integrated Air Pollution Index (IAPI) in all the provincial capital cities in China from 2003 to 2014 and clustered them into six urban development patterns. These patterns are as follows: inverse U-shaped, N-1-shaped, N-2-shaped, U-shaped, linear decline, and stable. The majority of the provincial capitals are N-1, N-2, and U types, suggesting that the air quality is deteriorating currently or will deteriorate in the future. Meteorological conditions and industrial structure are taken into consideration when testing the environmental Kuznets curve (EKC) hypothesis between the economy and air pollutant concentration. Results show that there exists no direct relationship between three main pollutants and GRP per capita, while an inverse U-shaped relationship with the secondary industry and a U-shaped relationship with the tertiary industry. These results will be a meaningful reference for policy makers to develop policies that coordinate the environmental protection and economic development.