Nitrogen Dioxide Rising in India, Nasa Air Quality Maps Show

The emission of the nitrogen dioxide pollutant has gone up significantly in the South Asia region, including India, during the 2005-2014 period, severely affecting air quality in the process, Nasa satellite maps show.

Nitrogen dioxide (NO2) is a yellow-brown gas that is a common emission from cars, power plants and industrial activity.

The US and Europe are among the largest emitters of nitrogen dioxide but both regions also showed the most dramatic reductions between 2005 and 2014, the maps showed.

"The main story in South Asia is increasing NO2 levels from 2005 to 2014 associated with booming economies and ambitious infrastructure development, such as new coal-burning power plants in the Chhattisgarh region of India," Nasa said in a statement.

"One of the largest increases occurred over Jamnagar (India), the site of the largest petrochemical complex in the world," it added.

"Dhaka (Bangladesh) had the largest increase (79 percent) of any world city," the statement noted.

Using new, high-resolution global satellite maps of air quality indicators, Nasa scientists tracked air pollution trends over the last decade in various regions and 195 cities around the globe.

"These changes in air quality patterns are not random," said lead researcher Bryan Duncan, atmospheric scientist at Nasa's Goddard Space Flight Center in Greenbelt, Maryland.

"When governments step in and say we are going to build something here or we are going to regulate this pollutant, you see the impact in the data," Duncan noted.

Duncan and his team examined observations made from 2005 to 2014 by the Dutch-Finnish ozone monitoring instrument aboard Nasa's Aura satellite.

One of the atmospheric gases the instrument detects is nitrogen dioxide.

Nitrogen dioxide can quickly transform into ground-level ozone, a major respiratory pollutant in urban smog. NO2 hotspots, used as an indicator of general air quality, occur over most major cities in developed and developing nations.

The science team analyzed year-to-year trends in nitrogen dioxide levels around the world.

They found that China, the world's growing manufacturing hub, saw an increase of 20 to 50 percent in nitrogen dioxide, much of it occurring over the North China Plain.

Three major Chinese metropolitan areas - Beijing, Shanghai, and the Pearl River Delta - saw nitrogen dioxide reductions of as much as 40 percent.

The findings were presented on Monday at the American Geophysical Union meeting in San Francisco, US and published in the Journal of Geophysical Research.