More than 9,200 challans were issued from November 3 to 6 against petrol and diesel vehicles for violating pollution control norms imposed under the Graded Response Action Plan (GRAP), Delhi Traffic Police said on Tuesday. The Centre for Air Quality Monitoring (CAQM) announced stage 4 of the GRAP after the Air Quality Index (AQI) reading surpassed the 450 mark and fell into the ‘severe plus’ category. In a release on Tuesday, the traffic police said 4,785 challans were issued for vehicles found without valid pollution under control (PUC) certificates. An additional 814 challans were issued against petrol vehicles compliant only with Bharat Stage-III (BS-III) emission norms and 3,656 against diesel vehicles compliant only with BS-IV emission norms. Paharganj, Kotwali, and Nangloi were among the 10 hotspots where challans were issued for vehicles without PUC certificates, the statement said. The traffic police also impounded petrol and diesel vehicles that are over 10 and 15 years old, respectively, in these four days, it added.