India, July 21 -- The environment ministry had issued a clarification on July 14 claiming that its July 11 order, exempting thermal power plants in India from using technology to trap sulphur dioxide emissions, was "grossly misinterpreted" following a backlash from experts terming it a retrograde step.

The July 11 notification reversed a key environmental policy notified in 2015 to cut SO2 emissions. The policy change means that about 78% of India's 537 thermal power plant units do not have to install machinery to reduce SO2 emissions, called Flue Gas Desulfurization systems (FGDs), that can filter 80-90% of sulphur emissions at the source.

Of the 537 units having annual generation capacity of 2,04,999 mega watt (MW) of electricity, whi...