Air pollution has decreased dramatically in parts of the Middle East in the past five years - partly due to armed conflicts since the Arab Spring.
A new study suggests the improvement is the result of the conflicts, economic recessions and human displacement suffered across the region.
The findings state: "A combination of air quality control and political factors, including economical crisis and armed conflict, has drastically altered the emission landscape of nitrogen oxides in the Middle East."
Jos Lelieveld of the Max Planck Institute for Chemistry in Mainz, Germany, was the lead author of the study, which was published in Science Advances.
Between 2005 and 2010, the Middle East had the world’s fastest-rising air pollution emission levels.
A similar increase took place in East Asia, most likely due to economic and industrial growth.
"However, [the Middle East] is the only region where this pollution trajectory was interrupted around 2010 and followed by a strong decline," Professor Lelieveld said at a press conference," the study said.
The research used satellite platforms to observe the emissions of nitrogen oxides in Middle Eastern countries over the last 10 years.
The results which show a sharp decrease could not have been predicted, the study says.
Prof Lelieveld said that "large changes of NO2 have occurred" in the Middle East in a "unique worldwide."
In Syria, the level of nitrogen dioxide over Damascus has fallen by 50 per cent since the start of the civil war in 2011.
"It's proportional to people, so if emissions have gone down in Syria by 50 per cent, I'd expect that 50 per cent of the people might have been displaced, as indeed they have," Prof Lelieveld said.
The findings "disagree with scenarios used in prediction of air pollution and climate change for the future," he added.
The study is the first to show the relationship between political stability and environmental factors in the Middle East.
By Alice Harrold