How Does Less Dust Make Pollution Worse?

It might sound counterintuitive, but new research from the Pacific Northwest National Laboratory in Washington, USA, suggests that dust might actually be beneficial for the environment in some ways.

By blocking out the sun’s rays through its presence, dust can limit how much the sun heats our land and groundsoil. Since wind patterns are dependent on the discrepancy between land and oceanic temperatures, less dust means less wind, which means greater contamination – especially over heavily populated and already polluted parts of China.

Catch-22

Large amounts of dust in the air are traditionally associated with poor air quality and increased pollution. But while their presence undoubtedly comes with some negative effects, they could also work to reduce pollution, too, because they can prevent solar rays reaching the Earth’s surface, thus increasing wind patterns and dissipating toxic chemicals.

This results in something of a Catch-22 situation, according to Professor Lynn Russell, who works at the Scripps Institution of Oceanography in the States.

“You're damned if you do, damned if you don't. Dust emissions can impair visibility, but they are not so harmful in terms of air quality,” she explained to the BBC. “If it's not a dusty year, you may be happy spending more time outdoors because you don't have this dust in the way, but you are actually going out to spend more time in more toxic air.”

Bad news for China

The dust deficit spells particular trouble for China, where the study was based. The country has been wrestling with poor air quality issues for many years now, with 1.6 million premature deaths attributed to contaminated airwaves every year.

In fact, it’s thought that Chinese power plants emit as much nitrogen oxides (NOx) as all of the passenger cars in the world – a staggering statistic. Without wind, these emissions remain hanging in the air above Chinese cities, thus having a severe long-term effects on its inhabitants.

Normally, naturally-occurring winds bring sand and dust from the Gobi desert, which acts as a microscopic but vital barrier between the sun and the Earth. By reflecting the sunlight back away from the ground, the dust can help to keep land temperatures down and improve wind circulation.

A miniscule cause, a monumental effect

While the amount of dust arriving from the Gobi desert can vary greatly, the actual effect this has on wind speeds appears at first glance to be negligible. Even the biggest discrepancies in dust concentration only affect wind speed by just over 0.1mph.

However, when extrapolated onto such a large landmass as China, these tiny changes in wind velocity can have a massive effect on air quality. Using computer software to model weather patterns over a 150-year period, the team found that there could be as much as 13% more pollution over the eastern side of China during the colder months.

With the government planning to spend £2 billion on cleaning up the airwaves of capital city Beijing, the knock-on effect that dust has on air quality shouldn’t be underestimated. It might sound crazy, but more dust just might mean less pollution for the Asian superpower.