BEIJING - Only three out of the 74 Chinese cities that were monitored for air quality last year reported clean air, while the large majority suffered various degrees of pollution, the Ministry of Environmental Protection said on Tuesday.

The three cities to meet government-set air quality standards are Haikou, capital of South China's Hainan province, Zhoushan in East China's Zhejiang province, and Lhasa, capital of Southwest China's Tibet autonomous region.

Beijing and its surrounding areas, including Tianjin and cities in North China's Hebei province, reported the heaviest pollution last year.

Thirteen cities in the region had on average 62.5 percent of days that failed to meet standards.

Among them, seven cities made the top-ten worst polluted city chart. The ten were Xingtai, Shijiazhuang, Tangshan, Handan, Hengshui, Baoding, Langfang, Jinan, Xi'an and Zhengzhou.

Forty-eight percent of days last year in Beijing had clean air, while 16 percent of days suffered heavy air pollution.

The ministry said air pollution was caused by coal burning and motor-vehicle exhaust.

Meanwhile air pollution was seasonal, the ministry said, as coal-fired heating in North China and unfavorable weather conditions made winter the most polluted season.

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