Are you really talking about electrolytic etching? Making the aluminium an anode in an electrolysis cell? This is an unsuitable procedure for aluminium because you will have to go to extraordinary lengths to cut out the simple production of aluminium oxide as the anode reaction, and the role of all of the other dangerous acids is simply to digest a rather intractable aluminium oxide layer that is forming.
My advice would be to forget this sort of etching for aluminium, and to go instead for ordinary chemical etching with caustic soda solution -- a much milder and more effective etchant that does not involve any deadly dangerous substances nor procedures, and certainly has no possibility of generating any noxious gases.
Even for an electrolytic etching, a strongly alkaline etchant will be much more effective at digesting any aluminium oxide layer that might form, and will certainly take noxious gases out of the picture.