Satellite images from NASA have shown a "dramatic" drop in pollution levels in China following the coronavirus lockdown.
The images show falling levels of nitrogen dioxide, which is emitted by cars and factories.
"This is the first time I have seen such a dramatic drop-off over such a wide area for a specific event," said NASA researcher Fei Liu, adding that it initially started to drop in Wuhan when roads and businesses were shut.
The images compared the first two months of 2019 with the same period this year.
The agency observed that the decline in air pollution levels also coincided with restriction imposed on transportation and business activities.
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