Could a Cadet heater release metallic dust into the air?

When the thermostat cuts off, two springy metal contacts are supposed to pop out of contact, which is supposed to completely halt the flow of electricity to the heater element.

If those contacts fail to completely separate, then a stream of sparks of electricity will jump across the (small) gap between them. This "arcing" will produce radiated and conducted electromagnetic interference which will disrupt electronic gear in the vicinity, produce a frying-bacon sound- AND create ozone plus microscopic spherules of melted and burnt contact material which can contain tiny amounts of copper, beryllium, iron, chromium or nickel depending on what alloy the spring contacts are made of.

Burning contacts are DANGEROUS because they can catch the heater on fire in addition to poisoning the air. THROW THE HEATER AWAY!