Here’s a hot tip on how to know that the air pollution in your country has gotten disgustingly bad. If you can’t distinguish between smoke from an hours-long factory fire and your normal, everyday smog, you’re just about there.

While it’s all well and good to know, from the numbers, that air pollution in China is bad, if you needed a more visceral image to help you understand just how bad it really is, consider that this smoke-smog confusion actually happened.

Voice of America reports:

The official Xinhua news agency says the furniture factory in Zheijiang province burned for nearly three hours before residents noticed the blaze. It took 10 hours to extinguish the flames, which destroyed a large amount of furniture.

Usually, when there’s a fire that big burning close by, YOU KNOW.

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