east asia

The US and Europe have shown a ‘dramatic’ reduction in nitrogen dioxide emissions between 2005 and 2014, although they continue to be the largest emitters of the poisonous gas.

While emissions were reduced by 20% – 50% in the US, they decreased by 50% in western Europe.

China has seen an increase in levels by 20% – 50%, according to the findings of a Nasa team.

Nasa scientists tracked air pollution trends over the last decade, using new high-resolution global satellite maps of air quality indicators.

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

Nasa Goddard Space Flight Center atmospheric scientist Bryan Duncan said: "These changes in air quality patterns are not random.

"Nasa scientists tracked air pollution trends over the last decade, using new high-resolution global satellite maps of air quality indicators."

"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."

The observations were made by a Dutch-Finnish ozone monitoring instrument onboard Nasa’s Aura satellite that detects the yellow-brown nitrogen dioxide gas.

Emitted from cars, power plants and industrial activity, nitrogen dioxide can transform into ground-level ozone, a cause of respiratory problems among the urban population.

The high resolution satellite captured data with better accuracy than previous low resolution ones, which missed variations over short distances.

Duncan said: "With the new high-resolution data, we are now able to zoom down to study pollution changes within cities, including from some individual sources, like large power plants."

The findings coincide with the climate agreement signed by 196 countries at the Paris climate summit. The countries agreed to limit their emissions to below 2C with the rich countries financing poor nations to meet their emission standards.

Image: The trend map of East Asia showing the change in nitrogen dioxide concentrations. Photo: courtesy of Nasa.