Science and technology: Air?pollution: Blown?away
Retired jet engines（退役喷射发动机） could help clear the smog that smothered big cities.To land at Indira Gandhi Airport is to?descend?from clear skies to brown ones.Delhi’s air is?toxic.According to the World Health Organisation, India’s capital has the most polluted atmosphere of all the world’s big cities.
The government is trying to introduce rules that will?curb?emissions—allowing private cars to be driven only on?alternate?days（私家车单双数出行）, for example, and enforcing better emissions standards for all vehicles. （可以为写作做积累）
But implementing these ideas, even if that can be done successfully, will change things only slowly.A quick fix would help.
And Moshe Alamaro, a researcher at the Massachusetts Institute of Technology, thinks he has one.
His idea is to take a jet engine, put it next to one of India’s dirty coal-fired power plants, point its?exhaust?nozzle（排气喷嘴） at the sky and then?switch?it on.His hope is that the jet’s?exhaust?will?disrupt?a meteorological?phenomenon?known as “inversion”, in which a?layer?of warm air settles over cooler air, trapping it, and that the rising?stream?of?exhaust?will carry off the tiny particles of matter that smog is?composed?of.Inversion exacerbates air?pollution?in Delhi and in many other cities, from Los Angeles to Tehran.（逆流，作为地理常识，了解起来哦）
A particularly?intense?example caused the Great Smog of London in 1952, when four days of air?pollution?contributed to 12,000 deaths.（历史的教训）
Dr Alamaro thinks a jet engine could?punch?through the inversion?layer?to create a “virtual?chimney” which would carry the trapped?pollution?above it, so that it could be?dispersed?in the wider atmosphere.He calculates that all the emissions from a gigawatt coal-fired power plant could be lifted away using a single engine with a nozzle speed of 460 metres a second.However, he has not?calculated?whether a jet engine could?disrupt?the inversion?layer?and allow the?pollution?to?escape?the city—so he is now going to test that?hypothesis.
Within eight months, Dr Alamaro plans to put one of his updrafters next to a coal-fired power plant and monitor what happens using a fleet of drones.He is in discussions with Tata Group, a?conglomerate?with an electricity-generating arm, to run it next to one of the firm’s power stations.