Mnemonic

A raging fire scorches the valley. A helicopter drops tons of earth to smother the blaze, but the dirt hitting the flames sends up a massive, choking wall of smoke that blacks out the sky for miles.
Additional thoughts
Picture the dramatic contrast: red fire below, helicopter above, brown earth falling, and gray smoke exploding outward when they collide. The earth doesn't extinguish the fire—it just creates more smoke.
Quick recall
A fire is smothered by earth dumped from a helicopter, unleashing a towering cloud of smoke.

Details

The keyword for 煙 is smoke. This kanji refers to the visible vapor and gases that rise from something burning, such as a fire, cigarette, or chimney. It encompasses both the literal phenomenon of smoke produced by combustion and can also be used figuratively to suggest something hazy, obscured, or elusive, much like a scene veiled in smoke.
On'yomi
えん
Kun'yomi
けむ.る、けむり、けむ.い