India plans to spray water over its capital

India plans to spray water over its capital, New Delhi, to combat toxic smog that has triggered a pollution emergency, officials said yesterday, with conditions expected to worsen over the weekend.

Illegal crop burning in farm states surrounding New Delhi, vehicle exhaust in a city with limited public transport and swirling construction dust have caused the crisis, as they do every year.

"Sprinkling water is the only way to bring down the dangerous pollution levels," said Shruti Bhardwaj, an environmental official charged with monitoring air quality.

The government was finalising the plans to spray the water from a height of 100 metres, which would be unprecedented, she said, without saying how much of the city of 22 million people would be covered.

The thick blanket of grey air and pollutants has enveloped Delhi for the past four days. A US embassy measure of tiny particulate matter, called PM 2.5, showed a reading of 523 at 9 am yesterday - the outer limit of "good" air is 50.

PM 2.5 is about 30 times finer than a human hair. The particles can be inhaled deep into the lungs, causing heart attacks, strokes, cancer and respiratory diseases.

The air has remained consistently in the "hazardous" category or beyond those levels in recent days, despite a litany of government measures - ordering a halt to construction, restricting car use and raising parking charges fourfold to persuade residents to use public transport.