A smoke grenade is a modern-era explosive
As an action, a character can throw a grenade at a point up to 60 feet away. With a grenade launcher, the character can propel the grenade up to 120 feet away.
One round after a smoke grenade lands, it emits a cloud of smoke that creates a heavily obscured area in a 20-foot radius. A moderate wind (at least 10 miles per hour) disperses the smoke in 4 rounds; a strong wind (20 or more miles per hour) disperses it in 1 round.
Source Dungeon Master’s Guide, page 267