Pollution
Several cities have banned fireworks because of air pollution.
The water filtration system is like one you'd find in a fish tank, but it's designed for an entire ocean.
It is the second ever "red alert."
Officials issued a "yellow alert" for smog in Shanghai this week.
WHAT'S HAPPENING
Smog in Chinese metropolis Shanghai hit its highest level since January on Tuesday.
For many Beijing residents face masks have become a routine cold-weather accessory.
Pollution has soared to abnormal levels in Beijing over the past few days.
The news comes just before a major global climate summit in Paris.
The fog caused massive flight delays.