A motorbike passes a chemical factory that discharges smoke in Hengdong.[YANG YI/CHINA DAILY]

On May 30, a group of experts with the Chinese Society For Environmental Sciences suggested guidelines for lawyers to follow to prove a link between pollution and a client's health complaint. The fundamentals were:

Confirm the type of pollutants and that environmental degradation has occurred

Find evidence that the pollution started before the client's health problem and that it is not an isolated case

Make sure the health complaint was not caused by an occupational hazard or is genetic

Wang Zhenyu welcomed the input from institutes and professional groups to help with environmental litigation, but he still has concerns.

NGOs have been encouraged to bring public-interest litigations against polluting companies since the revised Environmental Protection Law took effect in January last year. "The number of these cases is rapidly increasing, too, but the results haven't been good," he said. "Some disputes are still hard to file, and it's equally hard to get courts to identify the severity of the damage caused by pollution."

Chinese courts heard 48 environmental public-interest lawsuits in 2015, while the total number between 2007 and 2014 was just 65, according to the Supreme People's Court.

Solving environmental disputes in China still has a long way to go, "not only in terms of filing cases, but also in technical knowledge so that courts can qualify how much damage has been done", Wang Zhenyu added.

Contact the writers at caoyin@chinadaily.com.cn and zhengjinran@chinadaily.com.cn