We all know how bad China’s air pollution is, however it has been discovered that man-made pollution in eastern China’s cities worsens when less dust blows in from the Gobi Desert. That’s right… when there is less natural dust blowing around the air quality for the millions of people who live there worsens.
This is because dust plays a significant role in shaping air temperatures, which promotes winds to blow away pollution. With less dust in the air, the air stagnates; this encourages the pollution to becoming more concentrated and then it hangs around much longer.
In a new study scientists found that reduced dust caused a 13 percent increase in man-made pollution over eastern China during the winter. However, the broader question of how natural dust and pollution interact with each other is an important one for everyone, not just China.
Using computer models and historical data, the researchers found that a reduction in natural dust transported from the Gobi Desert in central and northern China, translated into an increase in air pollution in highly populated eastern China.
The reason for this the Pacific Northwest National Laboratory explained:
“That natural dust particles in the air help deflect sunlight. Fewer dust particles translates to a warmer-than-usual land surface and cooler-than-usual water.
“That reduces the temperature differential in winter between sea and the land, resulting in weaker winds — and increased air stagnation.
“As a result, during the winter monsoon season, eastern China experiences weaker winds when there’s less natural dust in the air.”
The amount of dust would go unnoticed; the researchers are talking of reduction barely more than one-tenth of one mile per hour. However, when taken over an entire region, what may seem to be a minor change has a huge effect on climate and air quality.
Post-doctoral researcher Yang Yang of PNNL, first author of the paper which was published in Nature Communications, said in a statement:
“This is one of the first times we’ve really looked at the interactions between natural dust, wind, and anthropogenic pollution.
“It turns out that dust plays an important role in determining the quality of the air for many people in eastern China.”
The modeling results had also matched observational data from dozen of sites in eastern China. It was found that up to two to three days after winds had carried dust into the region, the air was cleaner than before the dust had arrived.
Even though it is important to understand the role of natural dust particles, man-made pollution is still the core of air pollution in cities like Beijing.