Human fingerprint on global air quality; NASA reveals all

This global map shows the concentration of nitrogen dioxide in the troposphere as detected by the Ozone Monitoring Instrument aboard the Aura satellite, averaged over 2014. Image courtesy: NASA

Zee Media Bureau

New Delhi: Air pollution, air quality, climate change, global warming and carbon footprints are those things that have become hot topics of debate.

The recently concluded summit on climate change held in Paris and the resultant deal that was made on the convention's final day, should be evidence enough regarding the magnitude of the environmental crisis.
Contributing their part to make the world aware of global warming and its impact, is none other than US space agency NASA, which has utilized its new, high-resolution global satellite maps of air quality indicators to track air pollution trends over the last decade in various regions and 195 cities around the globe.

(The trend map of the United States shows the large decreases in nitrogen dioxide concentrations tied to environmental regulations from 2005 to 2014. Image courtesy: NASA)

NASA's science team analyzed year-to-year trends in nitrogen dioxide levels around the world. To look for possible explanations for the trends, the researchers compared the satellite record to information about emission controls regulations, national gross domestic product and urban growth.

(The trend map of East Asia shows the change in nitrogen dioxide concentrations related to a mix of economic growth and environmental controls across China, South Korea and Japan from 2005 to 2014. Image courtesy: NASA)

The space agency's studies revealed that the United States and Europe are among the largest emitters of nitrogen dioxide. Both regions also showed the most dramatic reductions between 2005 and 2014. Nitrogen dioxide has decreased from 20 to 50 percent in the United States, and by as much as 50 percent in Western Europe.

(The trend map of the Middle East shows the change in nitrogen dioxide concentrations from 2005 to 2014. The decreases in Syria are tied to the economic disruption caused by their civil war. Image courtesy: NASA)

Researchers concluded that the reductions are largely due to the effects of environmental regulations that require technological improvements to reduce pollution emissions from cars and power plants.

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, whereas, the South African region encompassing Johannesburg and Pretoria has the highest nitrogen dioxide levels in the Southern Hemisphere, but the high-resolution trend map shows a complex situation playing out between the two cities and neighbouring power plants and industrial areas.

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