TNPCB chairman himself conducts surprise checks Tirupur: The Tamil Nadu Pollution Control Board (TNPCB) on Tuesday ordered closure of 75 dyeing units in the city and its suburbs for its failure to comply with the directives of Supreme Court pertaining to pollution caused by dyeing units on River Noyyal. The action was taken following surprise checks carried out at the various dyeing units by the TNPCB chairman R. Balakrishnan and his team. Of the 75 units, 74 were attached to the Angeripalayam Common Effluent Treatment Plant (CETP) and one had Individual ETP on its premises.