An expert committee appointed by the National Green Tribunal (NGT) has found the emissions from all the stacks at the Sterlite’s copper unit at Tuticorin to be “within the permissible limit” prescribed by the Central Pollution Control Board when the plant was in normal operation.

The committee is headed by Prof. P. S. T. Sai from IIT Madras.

The committee is given the brief to measure emissions, and examine the working conditions of machinery at the copper unit of Sterlite Industries at Tuticorin.

The terms and references of the committee were clearly defined, and the NGT had given it April 29 deadline to submit the report.

While arriving at this conclusion, the committee relied on manual monitoring of all the five stacks as well. The committee visited all the ambient air quality monitoring stations, maintained by both Sterlite and Tamil Nadu Pollution Control Board (TNPCB).

The sampling and analysis of the ambient air quality were independently done by Sterlite and TNPCB. “The analysis results by both the parties were almost similar, and were well within the permissible limit,’’ the expert committee said in its report.

The expert panel also inspected the calibration of online SO2 analyzers, and found that the “instruments are calibrated properly and working well”. After examining the routing of gas from the stack to the analyzers, the committee found everything to be ‘in order’.

The TNPCB ordered the closure of the plant on March 29 after local residents complained about noxious emission. Sterlite is a unit of London-listed Vedanta Resources plc. On April 1, the company filed a petition before the National Green Tribunal in Chennai challenging the TNPCB order. The case has since been transferred to the Delhi court of NGT.

The TNPCB ordered the closure of the plant, which produces more than 300,000 tonnes of the metal a year, on March 29 after local residents complained about noxious emissions.

Sterlite has said the plant’s emissions are within permissible limits. On April 1, Sterlite filed a petition in the National Green Tribunal in Chennai challenging the order of the state pollution control board.