When a component is lasered an amount of the substance is thermally decomposed (burnt off).
This thermal decomposition, which is the fume, comprises a mixture of particulate and gas. Glass, ceramic and most base metals do not generate as much fume, so we will concentrate on polymers which do.
The gaseous organic compounds are known as Volatile Organics Compounds, VOCs. The table below shows the ratio of particulate to gas for a variety of plastic materials and various chemical compounds produced when lasering various polymers.
Non organic gases given off, that need capturing, tend to be acidic eg HCI and for these applications a specifically designed media for acid gases is included in the gas filter.