India has the world's most toxic air, said a new study released lately at an international forum, confirming earlier research results that the country is faced with serious air and water pollution.

The international study, led by Yale and Columbia Universities in the United States, compared air quality with regard to its effect on human health in 132 nations worldwide to reach the conclusion.

India has secured the last place in the study report by scoring a minuscule 3.73 out of 100 points, lagging far behind the next worst performer, Bangladesh, which managed to score 13.66 points, The Hindu newspaper quoted the report as saying on Saturday.

In fact, the entire South Asian region fares badly, with Nepal and Pakistan taking up the remaining spots in the bottom four of the rankings, according to the study presented at the World Economic Forum currently taking place in Davos, Switzerland.

On the other hand, though in the overall rankings -- which takes 22 policy indicators into account -- India fared minimally better, but still stuck in the last 10 ranks along with environmental laggards such as Iraq, Turkmenistan and Uzbekistan, said other statistics.

In the case of water -- both in terms of the ecosystem effects to water resources and the human health effects of water quality -- India performed poorly, whereas Switzerland, Latvia and Norway captured the top slots in the chart.

Air pollution has been an irritant in India for long.

Last year, a local study into the health effects of air pollution in the country had revealed that Indians have the poorest lungs among 17 populations across four continents.

According to government statistics, the major sources of air pollution in India include the rampant burning of fuel wood and biomass such as dried waste from livestock as the primary source of energy.

As of 2009, majority of Indians still use traditional fuels such as dried cow dung, agricultural wastes and firewood as cooking fuel. This form of fuel is an inefficient source of energy as its burning releases high levels of smoke, PM10 particulate matter, polyaromatics, carbon monoxide and other air pollutants.

The World Health Organization also estimates that 300,000 to 400,000 people die of indoor air pollution and carbon monoxide poisoning in India because of biomass burning and use of chullahs or indigenous stoves.