中国の大気汚染、新型ウイルスで減少　ＮＡＳＡ衛星画像で判明

【ワシントンＡＦＰ＝時事】米航空宇宙局（NASA）は、中国の大気汚染が激減したことを示す衛星画像を公開した。新型コロナウイルスの感染拡大に伴う経済活動の停滞に「部分的に関係している」という。（写真は資料写真）
　ＮＡＳＡと欧州宇宙機関（ＥＳＡ）の衛星が収集したデータを解析した科学者らによると、二酸化窒素（ＮＯ２）汚染の減少はまず、同ウイルス流行の中心地である武漢付近で始まり、その後中国各地に拡大した。
　ＮＯ２濃度を比較した地図では、武漢などで厳しい隔離措置が取られる前の１月１～２０日と２月１０～２５日の間で顕著な濃度低下があったことが示されている。
　ＮＡＳＡのウェブサイト「アース・オブザバトリー」には、「この変化は、コロナウイルスの感染拡大を受けての経済活動の停滞に、少なくとも部分的に関係していることを示す証拠がある」と記されている。
　中国当局は、ウイルスの封じ込めを目指して徹底した措置を講じており、移動制限や工場の一時閉鎖、また流行の発生地となった主要産業地帯の湖北省の隔離に踏み切っている。
　ＮＯ２は車や発電所による化石燃料の燃焼に伴って発生し、ぜんそくなど呼吸器系の問題を引き起こす恐れがある。
　ＮＡＳＡの研究員は、「特定の事象によって、これほど広範囲で劇的な減少が確認されたのは初めて」と話している。ＮＯ２の減少は２００８年の世界金融危機の際にも数か国で確認されていたが、減少ペースは緩やかだったという。【翻訳編集ＡＦＰＢＢＮｅｗｓ】
〔ＡＦＰ＝時事〕（2020/03/03-13:13）

NASA satellite images show a dramatic fall in pollution over China that is partly related to the economic slowdown due to the coronavirus outbreak, the space agency said.
The reduction in nitrogen dioxide (NO2) pollution was first noticed near Wuhan, the epicentre of the outbreak, but eventually spread across China, according to NASA scientists who examined data collected by their and European Space Agency satellites.
Maps comparing NO2 concentrations showed a marked decline between January 1-20, before a sweeping quarantine was imposed on Wuhan and other cities, and February 10-25.
There is evidence that the change is at least partly related to the economic slowdown following the outbreak of coronavirus, NASA's Earth Observatory said in a statement.
Chinese authorities have taken drastic steps to contain the virus, curbing the movement of people, temporarily closing factories across the country and quarantining central Hubei province, a key industrial region where the epidemic first appeared.
NO2 is a byproduct of fossil fuel combustion in vehicles and power plants and can cause respiratory problems, such as asthma.
This is the first time I have seen such a dramatic drop-off over such a wide area for a specific event, Fei Liu, an air quality researcher at NASA's Goddard Space Flight Center, said.
The 2008 global financial crisis saw a decrease in NO2 over several countries but it was a gradual fall, she said.
This year's fall came during the Lunar New Year, when factories and businesses close, but researchers believe the decline is far greater than could be attributed to the holiday period.
NO2 concentrations over eastern and central China were 10-30 percent lower than what is normally observed over the time period.
And there has not been a rebound in levels after the holiday.
This year, the reduction rate is more significant than in past years and it has lasted longer, Liu said.
I am not surprised because many cities nationwide have taken measures to minimize spread of the virus.
A separate study in February found China's carbon emissions had dropped by least 100 million metric tonnes in the previous fortnight -- nearly six percent of global emissions during the same period last year.
According to a study by the Centre for Research on Energy and Clean Air in Finland, the rapid spread of the coronavirus led to a drop in demand for coal and oil, resulting in the emissions slump.