A total of 70.6 percent of the 74 Chinese cities monitored for air quality in April met the national air quality standards, the Ministry of Environmental Protection said on Friday.
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The Pearl River Delta reported the best air condition with 93 percent of the cities reaching the air quality standards, and there were no days of heavy pollution.
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East China's Yangtze River Delta performed slightly worse last month. Twenty-five cities there reported air pollution on 21.8Â percent of the days, including heavy pollution on 0.3 percent of the days.
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Beijing and its surrounding areas, including Tianjin and cities in north China's Hebei Province, reported the heaviest pollution last month.
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Thirteen cities in the region had on average 65.2 percent of days that failed to meet standards.
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Among them, ten cities made the top-ten worst polluted city chart. The ten were Xingtai, Tangshan, Shijiazhuang, Jinan, Handan, Baoding, Tianjin, Qinhuangdao, Beijing and Langfang.
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Six of the monitored cities reported 100 percent clean air last month, including Shenzhen, Haikou and Zhoushan.
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The primary key air pollutant is PM2.5, accounting for 58.4 percent of the days that failed the air quality standards, the ministry said.Â