Technically, any industry was pollution-prone if they have a discharge or an emission, she said answering queries during an online chat, organised by the Environment Information Centre of the State Environment Department recently.

She said any industry that generated sewage or effluent was potentially polluting. However, the Pollution Control Board could consider providing its consent if the application was submitted to it.

Sewage treatment plants too would have to get environmental clearance from the Board, which, she said, encouraged more recycling plants for wastewater. Besides, work to clean up the city waterways was in progress, supervised by the Environment Department.

Answering questions on municipal wastes, Ms. Vaidyanathan said every municipality should have proper plan for disposal of solid waste, including recycling, composting and land filling. Every municipality should comply with the Municipal Solid Waste Handling Rules, as per the legislation. The Chennai Corporation, she said, has prepared an action plan for solid waste disposal.

While plastic waste was already being recycled in a small scale, better segregation of wastes would encourage more recycling. Paper bags, for example, should go to paper recyclers while batteries should be segregated and sent to a secured landfill.

She said the Board was working with the Central Leather Research Institute to improve the performance of effluent treatment plants in the leather industry. Larger leather units were also being encouraged to put up reverse osmosis plants. To a specific complaint about a polluting cement factory in Washermanpet, she promised immediate action. The standards for particulate matter emission have been improved to reduce air pollution and cement factories should conform to the new standards, she added.