What are the BS-III norms, which have been banned by the SC?
The Bharat Stage (BS) emission standards, introduced in 2000, were set up by the Centre to regulate air pollutants emitted by vehicles. Under the BS-III norms, regulations were put on vehicular pollutants like carbon monoxide, nitrogen oxides, and particulate matter among others. BS-IV compliant vehicles cause nearly 50% less pollution than BS-III compliant ones.