?? lot of complaints have been brought to our notice that these (auto emission) checking centres are not working properly and their instruments are not being properly calibrated? It will be the responsibility of the state government to see all these checking centres work properly?? ? Calcutta High Court, March 30, 2004, with reference to S.M. Ghosh?s petition on Calcutta?s foul air.

Fifteen months later, last Friday, the high court disposed of the petition following a submission by Ghosh?s lawyer ? backed by the government ? that the testing centres across the city had been computerised, and that they were ?working properly?.

Metro had on Saturday blown the lid off the malpractice rampant in some of the pollution under control (PUC) centres where polluting vehicles were being given ?authentic? computerised clean chits without emission tests being conducted.

The public vehicles department has reacted by ordering a detailed inquiry into the ?problem?. Metro takes its fight against the fudging of fume figures forward by highlighting the modus operandi adopted by some PUC operators as well as car-owners or drivers to pass the pollution test, by crook more than hook.

SOFTWARE SABOTAGE: The software attached with the four-gas analyser (for petrol) and smoke meter (for diesel) is being manipulated, often with some inputs from the company supplying the machine. The machine is in place but no emission test is conducted.       

FORMAT FOUL-UP: Indigenous computer skills are used to prepare something of a template for false certificates, to be doled out by the dozens.

Such certificates can be obtained from centres that have a non-functional test set-up. Common in districts.

NUMBER PLATE PROXY: The owner of a Vehicle A (pollutant) spends just Rs 50 to paint his number on to the plate of Vehicle B (clean) of the same make.

Vehicle B passes the pollution test but wins a certificate in the name of Vehicle A. Common among buses and minibuses.

In case of taxis, swapping of number plates before taking the test is par for the course.

TAILPIPE TAMPER: The smoke-flow pipe connecting the tailpipe with the smoke meter is fixed to ensure that the full effect of the emission is not recorded.

NO ENTRY: The sampling probe (emission sensor), going by the book, should reach 300 mm into the tailpipe for accurate measurement.

Instead, it is barely kept at the mouth of the tailpipe by centres looking for lower readings. Also, autorickshaws are notorious for bending the tailpipe to prevent the sensor from conducting a proper probe.

These are just some of the methods of malpractice in a ?foolproof? system touted as the guardian of the city?s lungs.