By Cang Wei in Nanjing

Jiangsu and Shandong provinces, the two regions with the most valuable chemical output, have made stricter environmental protection policies and closed many chemical plants following a blast in Jiangsu's Xiangshui county that killed 78 people in March.

The provincial government released a plan earlier this week calling for closure or relocation of all chemical plants within 1 kilometer of the Yangtze River and outside a designated chemical industry park by the end of 2020.

No chemical parks or projects will be built or expanded inside the 1 km zone, and factories failing to meet environmental protection standards will be closed.

Qualified factories are being encouraged to move to nearby chemical parks. Those that cannot be closed or relocated must move nearby residents to safer places.

Jiangsu has 53 chemical parks, with seven of those ranking in the country's top 30 in output - especially pesticides, dyes and petrochemicals. Jiangsu's chemical industry revenue reached more than 2 trillion yuan ($295 billion) in 2017, ranking second in the country in total output, behind Shandong province.

In 2017, Jiangsu had more than 5,000 chemical factories. Now it has 1,660 chemical enterprises that produce less than 20 million yuan annually, 71 in environmental sensitive areas and 34 outside chemical industrial parks closer than 1 km to the Yangtze.

Shandong province, whose total chemical output value leads the country, has closed more than 400 chemical factories since April 1.

The province has more than 9,000 chemical factories and has closed or relocated 600 of them and suspended 2,000 since the second half of 2017.

Li Chunhua, director-general of Green Stone Environmental Protection Center, an NGO in Nanjing, Jiangsu, said the plan is comprehensive and focuses on solving safety problems.

"More government information disclosure and public supervision should be encouraged," Li said, adding that public supervision is an effective supplement to government regulation and companies' self-discipline, but it was not mentioned in the plan.

"Increasing the factory leaders' consciousness of environmental protection is more important," he said. "They should pay attention to environmental protection in all aspects of management."

The blast in Xiangshui on March 21 at the Xiangshui Chemical Industrial Park in Yancheng, Jiangsu, injured hundreds of people and led to the closure of the entire chemical park.

Jinan, Shandong province, and Ulaanqab in the Inner Mongolia autonomous region both reported deadly production accidents in April, with 10 people killed at Qilu Tianhe Pharmaceutical Co in Jinan and four dead and 35 injured at Dongxing Chemical Co in Ulaanqab.

On April 29, the State Council's Workplace Safety Commission ordered leading officials in the two cities to take effective measures to ensure the safe production of hazardous chemicals, Xinhua News Agency reported.