Chennai is a city where vehicular population has grown by leaps and bounds and alongside, so has exhaust pollution.

In a study on air pollution in urban areas in 2012, titled ‘Urban Air Pollution and Co-Benefits Analysis for Indian Cities–Pune, Chennai, Indore, Ahmedabad, Surat and Rajkot,’ by S.K. Guttikunda and P. Jawahar, Chennai has been ranked first in PM10 (vehicle exhaust pollution) emission at 50,200 tons per year, compared to other cities.

The reason for the air pollution is there for everyone to see — vehicles that do not conform to emission norms. In 2010, the Central government set emission standards whereby new four-wheelers and heavy vehicles registered in 13 cities, including Chennai, should have Bharat Stage IV engines. But the standards are violated by vehicle owners who opt for Bharat Stage 3 norms because of the big price gap between the two.

A regional transport officer (RTO) in north Chennai said, normally, there is a minimum cost difference of Rs. 30,000 and above between Bharat III and IV vehicles. Vehicle owners do a little trick to circumvent this extra charge: they register their vehicles outside Chennai metropolitan area, in places such as Ponneri, Kundrathur and Padappai.

The RTO said vehicle owners are able to register outside their place of residence owing to a loophole on residential proof.

A sworn affidavit need simply say that the owner does not reside at the mentioned address.

Here’s a little description on the fine art of whistle-blowing in an MTC bus, and we mean, actually putting a whistle to one’s mouth and blowing it.

The number of whistles blown by the conductor signal to the driver to move, halt or even overtake another bus. Some conductors have customised tunes to alert passengers of upcoming stops or warm them of the presence of a pickpocket inside the bus.

There are four types of signals using the whistle. “While a single whistle signals the driver to halt the bus, a double whistle indicates the driver should start the bus,” said a conductor. A series of long whistles with breaks is a signal to overtake another bus or allow another vehicle to do so. “A continuous whistle is a signal to apply sudden brake. This is done during an emergency situation,” he said.

Though these are standard signals, some conductors use the whistle to display their artistic abilities. “During my college days, conductors had different tunes for various bus stops. Especially if the bus passed through women’s colleges,” said P. Naresh Pandian, a businessman who studied in Chennai and is now settled in Kodaikanal.

According to conductors, in several other States, a long rope attached to a bell is used instead of a whistle. “We had it in Chennai too. But miscreants began to misuse it; they would pull the rope unnecessarily and mislead the driver,” said a member of MTC’s conductor union.