Stricter controls

Messages left on the hotline and special email box exposed more than 26,000 heavily polluting companies, whose details were passed on to the relevant governments. That resulted in the imposition of strict punishments, such as heavy fines and more than 20,000 businesses being ordered to suspend production.

"The strict investigations provided solutions to many long-standing thorny problems," said Chang, from the development research center.

In one case, a pharmaceutical factory in Hulunbuir, Inner Mongolia, was reported 80 times during the one-month inspection period because of the pungent odor it released.

"Environment bureaus at the city and autonomous region levels had punished the plant 29 times, using a combination of administrative penalties and short periods of detention, but it remained in production, generating the smell," according to a statement released by the autonomous region's government.

Following the inspections, the local government conducted a thorough investigation, which resulted in two people at the plant being detained and production being suspended, the statement added.

Ma Yong, an environmental law researcher at the Supreme People's Court legal center, said the administrative punishments levied have not been strong enough to curb the activities of some polluters. However, the work of the central-level inspectors had helped the local government to impose tougher controls to rein in polluters. The measures have brought the problem under control in some regions.

Ma said it would be helpful if local governments adopted legal measures against pollution, such as fully implementing the revised Environmental Protection Law, instead of relying on short-term inspections.

Zhang Xiaode, director of the Ecological Civilization Research Center at the Chinese Academy of Governance, said the inspections had been effective and sent out a signal that the environment is related to social and economic growth.

The investigations have also helped the central and local governments to formulate solutions to problems, resulting in more effective efforts to improve the environment, he added.