Currently, the smoke is client side, not server side. Smoke also cannot be seen from a certain distance, this means it's only useful during mid-range combat.
Smoke grenades are a throwable device packed with a mixture of potassium chlorate, lactose, and typically a dye for signalling. The chemicals mix with air to create a smoke screen that temporarily removes battlefield awareness.
~ In-game description
Update #38 (Season 6 - Update 6.2) - vN/A
Decreased fuse time from 3 seconds to 1 second.
Pre-release #32 (Season 4 - Update 4.2) - vN/A
Throwables Friction Adjustment
Adjusted the friction force of throwables to make rolling movement more consistent and predictable.
Friction force has been increased to slow rolling speed and cause them to roll a shorter distance after impacting surfaces.
Smoke Grenade Improvement
Smoke grenades are now more accurately synchronized across all players and observers.
Previously, smoke grenade duration for the viewer would start when coming into viewable range (1 km) of the smoke grenade. Smoke grenade plumes will now end at the same time for all players/observers.
Pre-Update #24 - vN/A
Smoke Grenades are spawned at a higher rate compared to other throwables.