Cutting expanded/extruded polystyrene (EPS/XPS) at a correct, low temperature produces relatively little fume, but you should still ventilate. The styrene vapour and fine particulates are irritants, and the hotter the wire the more you make. Cut near an open window, use a small fan to pull fumes away from your face, or build a simple extraction hood.
Avoid cutting PVC foam or anything containing chlorine — it can release hydrochloric/toxic gases. Polyurethane foam does not hot-wire well and gives nastier smoke. Keep the wire as cool as the cut allows (which also improves quality), do not cut in a sealed room, and wear a mask if you do long sessions.
Avoid cutting PVC foam or anything containing chlorine — it can release hydrochloric/toxic gases. Polyurethane foam does not hot-wire well and gives nastier smoke. Keep the wire as cool as the cut allows (which also improves quality), do not cut in a sealed room, and wear a mask if you do long sessions.