煙 smoky

The fire on the west side of the earth made the air too smoky to ENJOY.

no smoking ★★★★☆
禁 (prohibition) + 煙 (smoky) = 禁煙 (no smoking)

smoking ☆☆☆☆☆ NP
喫 (enjoy a drink and a smoke) + 煙 (smoky) = 喫煙 (smoking)

the act of smoking. You'll see this on signs a lot, meaning 'this is the smoking section.'