An inspection campaign carried out in 14 major cities last year has led to considerable progress in controlling air pollution, the Ministry of Environmental Protection said on Thursday.

A team from the ministry inspected the cities, most of which are in the north of the country, between April and August. As a result, local governments are putting a greater emphasis on curbing pollution and have taken a number of measures to tackle the problem, Liu Changgen, the head of the team, said.

The team recently visited the cities again and found that they had closed or upgraded a number of enterprises that were discharging pollutants at levels that breached regulations.

The environmental authorities of some of the cities have hired more law-enforcement officer and introduced new environmental monitoring facilities to improve supervision, Liu said.

However, the latest inspections showed that some problems remain. They include a lack of measures to deal with pollution caused by the burning of coal, and the fact that some enterprises continue to breach the regulations covering the discharge of pollutants.