"Only 30 percent of pollution in Paris is due to the factors in Paris. The fraction that is locally produced is actually 10 percent.
In Delhi also most of the pollution does not come from Delhi but regionally...A lot of things do not come from Delhi itself," said Andre Prevot, an expert in aerosol at Switzerland's Paul Scherrer Institute.
Aerosol is a very fine particle of liquid and solid suspended in gas that causes pollution. Prevot was speaking at a conference on aerosol organised at the Physical Research Laboratory here.
On the problems of pollution in Delhi, Prevot told PTI that burning of crop stubble in the neighbouring states caused significant pollution after Diwali. "Crackers were a factor. But the main reason behind Delhi problem was wind coming from north at exactly the period when crop stubble was being burnt.
The whole Punjab was on fire. All factors formed a lot of aerosols. It's a combination of all these factors," he said. "Burning is a really important factor and it should be avoided. It should be converted to energy source.
Within Delhi, I am not very sure, but it is important also to take care of roads. Traffic causes dust. If they improve their roads, housing situation, it will reduce aerosol level," Prevot said. He said to address the problem and improve the situation, policy makers should look at around 500 to 1,000 km of areas.
"You will have to look at 500 to 1,000 kms of areas to improve the situation. It should look upwind for 500 km, like Punjab. That's what they have done in China," he added.
The expert said living in Delhi can reduce one's life by around 5-6 years due to air pollution. He also said cooking is causing addition of organic aerosol in the air, thereby adding to the pollution level.
"A new source of pollution is cooking organic aerosol. Cooking is an important component. A fraction of cooking organic aerosol is really big in a lot of places, especially when using oil or meat, with places having lots of restaurants," he said, citing the example of Beijing.
The three-day conference, organised by Indian Aerosol Science and Technology Association (IASTA) on Aerosol and Climate Change, will have lectures, contributed papers and exhibitions of products and systems related to aerosol science by researchers and experts who have converged here from country and abroad.