Air quality 'improves in Calcutta'

Air quality has improved in the Indian metropolis of Calcutta thanks to a ban on commercial vehicles, it has been reported.

The 15-year-old vehicles, which are believed to emit toxic fumes, were prohibited from travelling the streets of the city following a ruling by the Calcutta High Court.

S S Bala, regional head of the Central Pollution Control Board, said that the effect of the ban will be most apparent after the monsoon season, when pollution is usually at lower levels due to the higher moisture content found in the air.

He expressed particular concern about the impact of Katatel, a petrol containing kerosene and benzene which is used to power so-called autorickshaws.

"Katatel is very harmful, as the emission of half-burnt fuel contains toxic substances which are carcinogenic," he told the Press Trust of India.

Meanwhile, another cause of harmful emissions could come from a rather surprising source, according to ScienceDaily.

The news provider reported last week that research from the California Institute of Technology found that air quality may be affected by secretions from trees, which can change the chemistry of the atmosphere.

Written by Joseph Hutton