Tamil Nadu Pollution Control Board (TNPCB) in the last few days raided three dyeing units and two bleaching units in the Tirupur knitwear cluster engaged in unauthorised operations and discharging effluents. The raids ended on Tuesday.

Of the five units, two of them are in the organised sector and the remaining were run without obtaining basic permission required from various departments concerned for running any industrial unit, TNPCB sources told The Hindu .