It is a very good idea to use a Respirator when painting aerosol paints. Almost every can of paint will include a warning that you should use one. Professional painters wear respirators. Graffiti artists bombing the underpass wear them. You should, too.
We stock Bandit Half Mask Low Maintenance Respirators or similar masks. These are Half Mask Low Maintenance, Medium size with a P95 Filter Class appropriate for bike painting projects. Paint in a ventilated area.
We include this mask in our Paint Project Kit which has everything you will need for a bike painting project bundled together for $40 (or $34 if you are also buying paint).