This TED Talk features environmental data scientist Angel Shoe, recorded live at TED 2018.

When is seeing, not believing?

A couple years ago, my friend sent me this photo from Urumqi, which is the capital of Xinjiang province in northwest China.

On this particular day, she couldn't believe her eyes.

Checking the quality of the air outside, using this app on her iPad,

the numbers were telling her the air quality was good,

one on a scale of 500.

But when she looked outside, she saw something much different.

Yes, those are buildings in the background.

But the data were simply not telling the truth of what people were seeing and breathing.

And it's because they were failing to measure PM2.5, or find particulate pollution.

When PM2.5 levels went off the charts in 2012,

or crazy bad, as the U.S. Embassy once described it in a tweet, Chinese netizens took to social media,

and they started to question why it was that they were seeing this disconnect between official

air quality statistics and what they were seeing and breathing

for themselves. Now this questioning has led to an environmental awakening of sorts in China,

forcing China's government to tackle its pollution problems. Now China has the opportunity

to become a global environmental leader.

But the picture that I'll paint for you today is one that's mixed.

There are some signs that are very promising,

and there are other trends that are more troubling that warrant closer attention.

But now let's go back to the story at hand.

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