Making a passenger address from the Flight Deck whilst wearing a Smoke Mask not impossible but the 'Darth Vader' type audio is hardly reassuring , probably better to delegate and focus on getting Aircraft on ground whilst avoiding hills around Valencia.
Cabin Crew have difficult dilemma, Smoke Mask generally the best idea but is does rather isolate you and makes communication difficult.
Not a nice situation to find yourself in but a successful outcome.
Real events are never perfect in their execution.
Any long term fume effects need to be considered.