The ammonium nitrate propellant used in the airbag inflator may degrade over time due to propellant degradation occurring after prolonged exposure to high absolute humidity, high temperatures and high-temperature cycling.
In the event of an airbag being deployed, the excessive internal pressure may cause the inflator body to rupture and metal fragments may pass through the cushion material causing injury to the occupants.
The Toyota Corolla models affected by this recall were manufactured between 2001 and 2011.
Source: Rapex Alert 37/2019 A12/1334/19