Poor efforts to cut coal use and upgrade the industrial structure in Shaanxi province contributed to a worsening in air quality last year in Xi'an and other cities, environmental inspectors from the central government said on Tuesday.

During a monthlong inspection that started on Nov 28, officials identified 1,309 pollution problems in the province, according to Li Jiaxiang, who headed the team of inspectors.

As of the end of February, 222 polluting companies had been shut down and 26 people found responsible for pollution were detained, the Ministry of Environmental Protection said in a statement.