"No Honking Day."

MUMBAI, India - Stop honking! That was the message sent out by traffic police Monday in India's busiest city.

Mumbai's police marked World Health Day, April 7, as a "No Honking Day."

They were trying to build awareness of the effects of noise pollution in India's financial and entertainment capital, where it sometimes seems as if the city's 1.5 million vehicles are honking their horns at the same time.

But on there was no perceptible drop in noise levels - not surprising in a country where honking the horn is seen as an integral part of driving.

"Nothing will change in one day, but we need to reach out to people to make people aware that this noise is not normal," said Harish Baijal, a deputy traffic chief.

Police said they planned to extend the experiment and were taking action against those who violated noise-pollution rules.

Over the past week, the police distributed stickers and strung up red banners showing a horn with a knot running through it.

Some 1,900 motorists have been fined since January for using blaring music while reversing and honking in silent zones near hospitals, schools and courts, Baijal said.

Trucks regularly paint the words "Horn Please" on their backs so they can tell if motorists want to overtake, while other cars, auto-rickshaws and motorcycles are often fitted with souped-up foghorns or blast a variety of tunes.

Some Mumbai residents tried to spread the message.

"Stop honking. Don't you know it's 'No Honking Day?"' yelled Rumita Dey, a housewife angrily tapping the car window of a motorist stuck in a traffic snarl in Mumbai's northwestern Juhu suburb.

Dey pointed to red posters nearby that were part of the "No Honking" advertising campaign.

The motorist took his hands off the horn long enough to shrug, before jamming his palm back on and inching forward.

Other motorists said they would hit pedestrians if they did not honk.

"There is so much noise on the roads, you must honk for people to hear you," said Umesh Chitre, a computer salesman driving a small car.

"How can you drive without honking?"