There are no more harmful fums in powdercoating then what you would have from any aerosols like WD-40, brake clean etc. I know lots of guys who have an old oven in their shop to powder small parts.
best advice before you powder anything is make sure the metal is really clean. Bead blasted is the best way to clean a part. And make sure you pre-heat any part to allow for out gassing.
If you don't pre-heat in some cases after you coat , the metal will produce small bubbles in the powder that you cannot get out unless you start again.