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Environmental Science

The Chemistry of Smog Formation in Urban Areas

Quick fact

The term 'smog' was coined in 1905 from 'smoke' and 'fog,' but today's urban smog is primarily photochemical, driven by sunlight reacting with car exhaust—not coal smoke.

Why this is interesting

You step outside on a sunny afternoon and see a brownish haze hanging over the city. Ever wonder how that smog actually forms?