The side air bags are mounted in the outboard sides of the front seatbacks.
When the air bag crash sensors detect a side impact of greater than moderate force, the system inflates the side air bag only on the side in which the vehicle was hit. The side air bag inflates quickly to reduce injury to the driver or front passenger's chest caused by directly hitting interior parts such as a door or window.
For more details about air bag deployment, refer to "SRS Air Bag Deployment Criteria".
(With Front Passenger Occupant Classification System)
In addition, the front passenger side bag is designed to only deploy when the front passenger occupant classification sensor detects a passenger sitting on the front passenger's seat. For details, refer to the front passenger occupant classification system.

Front Passenger Air Bag
Curtain Air BagsMazda 6 Owners Manual: Supplemental Restraint System (SRS) Precautions
The front and side supplemental restraint systems (SRS) include different types
of air bags. Please verify the different types of air bags which are equipped
on your vehicle by locating the “SRS AIRBAG” location indicators. These indicators
are visible in the area where the air bags are in ...
Mazda 6 Owners Manual: Locking, Unlocking the Doors
NOTE
The system may not operate if you are too close to the windows or door
handles.
If the key is left in the following areas and you leave the vehicle,
the doors may be locked depending on the radio wave conditions even if the key
is left in the vehicle.
Around the dashboard
...