Atmospheric Sciences News

Reduced Middle East Air Pollution Linked to Societal Disruption

Invasions, armed conflict, sanctions, and economic distress correlate with cleaner air in high-resolution satellite data that reveal air quality at the individual city level.

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Many areas in the Middle East have experienced rapidly declining air pollution emissions, and these decreases could be due to political conflict, according to a new study.

While investigating air pollution levels across Europe, Asia, and the Middle East between 2005 and 2014, a research team led by Jos Lelieveld, director of the Max Planck Institute for Chemistry in Mainz, Germany, observed a striking reversal: From 2005 to 2010, many cities in the Middle East ranked among the fastest growing air pollution emitters. Then, starting around 2010, sharp declines in certain emissions began in many of those same cities.

Although some of the decline reflects the effectiveness of recent environmental cleanup measures by governments such as that of Saudi Arabia, that’s only a small part of the picture, the researchers say.

“A combination of air quality control and political factors, including economical crisis and armed conflict, has drastically altered the emission landscape,” the researchers reported last week in Science Advances.

Nitrogen Dioxide and Sulfur Dioxide

Using measurements from the Ozone Monitoring Instrument aboard NASA’s Aura satellite, which orbits Earth 14 times per day, Lelieveld and his colleagues studied the abundance of nitrogen dioxide, a highly reactive gas. Nitrogen dioxide, or NO2, belongs to a class of gases known as NOx that originate mainly from the combustion of fossil fuels but also from agriculture and natural sources.

The researchers also looked at emission trends of sulfur dioxide, a by-product also of fossil fuel combustion in power plants, industrial activities, and transportation, including burning of low-quality fuels in cargo ships.

Both NO2 and sulfur dioxide are well-known pollutants that can cause adverse health effects and also contribute to climate change.

Emissions Swings Reflect Unrest

The research team observed dramatic changes in emissions levels in cities across the Middle East, where a variety of different circumstances could have contributed to the variations.

In Iraq, for example, researchers mainly saw increases in NO2 until 2013, then a decrease in cities such as Tikrit and Samarra, which have recently been occupied by the Islamic State. Similarly, emissions in Baghdad began to decrease in 2010, around the time when activities of the Islamic State began, and began to increase in areas outside of Baghdad as people fled the city, Lelieveld said.

Mass migrations can also affect NOx emissions, the authors wrote. As a violent civil war ravaged Syria, 1.2 million people sought refuge in neighboring Lebanon. Between 2005 and 2013, the authors report, NO2 emissions increases over Lebanon ranged from 3% to 4%, soaring to 20%–30% in 2014.

In Egypt, political uprisings in early 2011 swept across the country, and during that period the satellite data reflect NO2 emission reductions that occurred parallel to a decrease in the country’s gross domestic product (GDP). Because no environmental or air quality policies were enacted during that time, the researchers suspect that a reduction in vehicle usage led to this drop in emissions.

Because declining NO2 emissions often paralleled a falling GDP, these declines could be due to higher fuel costs, reduced vehicle use, or stagnating industrial activities, Lelieveld said.

Impact of Sanctions

In Iran, the researchers found relatively high levels of NO2 emissions in major cities such as Tehran and Esfahan in the years before the United Nations imposed economic sanctions in 2006. After these sanctions were tightened in 2010, NO2 emissions decreased by 4% per year, parallel to a decreasing GDP that fell 6% per year starting in 2012.

In addition, the researchers found that sulfur dioxide emissions also fell 50% as economic sanctions slashed the volume of shipments, including oil exports, from and to Iranian ports, Lelieveld said.

“Since NO2 pollution is a very effective indicator of economic activity, satellite measurements of NO2 reduction help to reveal in a timely manner how political conflicts affect the socioeconomics,” said Jintai Lin, an atmospheric scientist at Peking University in Beijing, China, who did not participate in the study. “The relation confirms that human activities—in this case, political conflicts—are effectively and rapidly perturbing the atmospheric environment,” he added.

—JoAnna Wendel, Staff Writer

Citation: Wendel, J. (2015), Reduced Middle East air pollution linked to societal disruption, Eos, 96, doi:10.1029/2015EO034647. Published on 24 August 2015.

© 2015. The authors. CC BY-NC 3.0