The contact owns a 2018 Honda Civic. The contact stated that while driving at 3 MPH, the front driver's side air bag unexpectedly deployed. There was no impact on the vehicle that could have caused the front driver's side air bag to deploy. The air bag warning light was illuminated after the front driver's side air bag was deployed. The contact stated that when the front driver's side air bag deployed, she leaned back and raised her left arm, resulting in a metal fragment from the air bag cutting her left thumb. There was also smoke coming from the air bag, which she inhaled; however, no medical attention was received. The contact pulled over to the side of the road and parked the vehicle. The contact inspected the vehicle for leaks but found none. The vehicle was restarted and driven to the residence. The vehicle was not diagnosed or repaired by an independent mechanic or dealer. The manufacturer was not made aware of the failure. The failure mileage was approximately 156,000.