Environmental hazards

Environmental hazards refers to objects in the environment that can damage a player, causing Environmental damage. These can either be map elements that directly damage players, and map elements that require interaction from players first before becoming lethal. In the latter case, the player that triggered them may be considered the killer for enemy players killed by the environment effects.

Environmental damage ignores all friendly fire settings and damages all players equally. Some environmental damage can even damage vehicles.

Fire
Some maps contain open flames that will set players on fire if they go over them.

Barbed wire
In Battlefield 1, Barbed Wire inflicts damage to players if the player comes in contact with them.

Crushed
Supply drop can crush players if it dropped on top of them, regardless of if the commander that dropped them is friendly or not.

Some maps in Battlefield 4 contain vertically opened and closed gates. If the gates land on a player or a vehicle, it will be destroyed.

Neutral vehicle
A vehicle without any users is considered a neutral vehicle. If all players had bailed from a fast-moving vehicle, that vehicle is able to perform roadkills against players from both sides, as long as it still has enough momentum.

Destruction/Levolution
Destruction can often times cause roofs or entire buildings to crumble. In Battlefield: Bad Company 2 and Battlefield 3, when all the walls on a floor of a building have been destroyed, it will collapse and will instantly kill anyone inside or on top of the building, and in a very narrow radius just outside the perimeter building.

In Battlefield 4, players next to or in direct contact with a Levolution structure when it's about to collapse will be instantly killed.

Explosive objects
Explosive objects release an explosion when damaged enough.