India, home to some of the most polluted cities, to start measuring air quality

Smog and fog envelop the Rajpath, the ceremonial boulevard, behind, as a police man, center, controls traffic in the morning in New Delhi, India, Wednesday, Feb. 5, 2014. (AP Photo/Tsering Topgyal)

NEW DELHI -- The country's top environment official unveiled a government program Friday that will eventually measure air quality across India, home to some of the most polluted cities in the world.

Over the next five years, the government will begin measuring eight major pollutants that affect respiratory health in cities with populations above 1 million, and then gradually expand the air quality index to the rest of the country, Environment Minister Prakash Javadekar told reporters. The index will warn residents when pollution levels rise past dangerous levels.

The World Health Organization said earlier this year that the Indian capital had the worst air quality in the world, surpassing Beijing, a statement that New Delhi has vehemently disputed.

Air monitoring sensors around the landlocked Indian capital routinely register levels of small airborne particles at hazardous levels, especially in winter. The levels are three to four times New Delhi's own sanctioned limit, rivaling Beijing.

Like the Chinese capital, New Delhi has gone through rapid economic development, raising living standards but also spewing out loads of pollution.

Decades of policies that favoured economic growth over environmental concerns have taken their toll. The numbers of cars on the roads of New Delhi have doubled in the last decade and years of booming construction has kicked up countless clouds of dust.

Javadekar said it wouldn't be "business as usual anymore" and the government was committed to improving air quality as part of a cleanliness drive Prime Minister Narendra Modi launched earlier this month.

There are various ways to measure pollution, but comparisons have generally focused on the microscopic particulate matter, sometimes called black carbon or soot, which can lodge in a person's lungs and fester over time.

In New Delhi, levels of what is called PM 10 -- or particulate matter that is 10 micrometers in size -- reached 400 micrograms per cubic meter last winter. That is four times the city's legal limit of 100, and well above the World Health Organization's recommended limit of 20.

While the Chinese capital acts aggressively on high pollution days -- closing schools and factories and taking government vehicles off the road -- India doesn't have a warning mechanism and until a few years ago the matter was hardly ever discussed.

The index will measure levels of PM 10 and the even tinier PM 2.5 as well six other indicators, including lead, ammonia, carbon monoxide and nitrogen oxide, and then calculate overall pollution. The warning levels will be colour coded and come with specific and easily understood health warnings, Javadekar said.

The plan will be up for review on the ministry's website for 45 days to seek public opinion.

The advocacy and research group Center for Science and Environment lauded the announcement, but said in a statement that the measures needed to be rolled out quickly to protect public health.