Six cities across Hebei, Henan and Shandong provinces have been named and shamed for failing to effectively tackle air pollution.

Twelve of 18 cities inspected so far in a monthlong crackdown by the Ministry of Environmental Protection have also been exposed for failing to deal with massive emissions violations by polluting companies.

Among the six that were shamed, the government of Jinan, capital of Shandong, for example, did not assess the performance of districts and departments in reducing air pollution last year, while plants in heavily polluted industries like cement and iron processing were not required to suspend production in winter, according to a statement from the ministry on Sunday.

Another of the six, Cangzhou, Hebei province, was also criticized for failing to draw up a detailed list for business shutdowns on heavily polluted days, which made it hard to achieve the desired effects of emissions reductions.

The four other cities among the six named were Baoding, Hebei province; Zhengzhou and Jiaozuo, Henan province; as well as Dezhou, Shandong province.

In addition to inadequate planning and poor implementation by some governments, the ministry's teams also exposed problems involving excessive and illegal discharges of pollutants by companies.

Inspectors found a metal processing company in Langfang, also in Hebei, discharging untreated pollutants because of damage to its scrubber, a pollution control device that removes particles or gases from emissions.

Chen Jining, the minister of environmental protection, and four vice-ministers have since Feb 15 been leading teams made up of 260 inspectors to review 18 cities, including Beijing, Tianjin, and others in Hebei, Henan, Shandong and Shanxi provinces.

All violations by companies have been reported to city and county governments to mete out penalties, the ministry said.

Chen headed the inspection team in conducting field surveys and holding talks with the leading officials of Baoding on Sunday and Monday.

"The shutdown of small yet highly polluting companies, which consume large amounts of coal and discharge massive pollution, should be accelerated," the minister said.

"Central or provincial inspections have been designed to find out and solve urgent environmental problems," said Wang Ande, head of environmental protection for Shandong.

Chang Jiwen, an expert in environmental policies with the State Council Development Research Center, said the inspection came at the right time.

By the end of this year, Beijing aims to lower the average daily concentration of PM2.5 - particulate matter with diameter of 2.5 microns or less that is hazardous to health - to 60 micrograms per cubic meter, which would be a reduction of 17.8 percent from last year.

Tianjin has a similar target, while Hebei has set a target of 67.

"If there is no clear drop in air pollution in the first quarter, the targets will become quite hard to reach for some cities," Chang said.