There are three main areas of consideration associated with the fume.
The effects it may have on the workforce coming into contact with it
The effects on the laser optics
The effects on the products being lasered
These particles fall within the respirable range and need to be removed from the working environment to prevent bronchial or lung damage.
The particulate generated in most laser applications is sub micron in size and as such almost all is respirable. This gives rise to two separate concerns:
1) The quantity of dust being inhaled.
Dust of any kind can also become a substance hazardous to health under COSHH when it is present at concentrations in the air equal to or greater than 10 mg/m3 (as a time weighted average over an 8-hour period) of inhalable dust or 4 mg/m3 (as a time weighted average over an 8 hour period ) of respirable dust. Marking applications typically generate up to 1mg/s of fume and Cutting applications in excess of 10 mg/s.
2) A reaction to the actual material of the particulate which may cause allergic, carcinogenic or toxic effects, for example, chrome and nickel compounds released from stainless steel are thought to be carcinogens.
Potential problems are usually associated with plastics which give off Volatile Organic Compounds when lasered, most of which have associated Occupational Exposure Limits (OEL). The table below covers a range of common plastics and lists the VOCs given off together with their OEL. PVC is worth a special mention in this context since it releases hydrogen chloride and small amounts of phosgene both of which are extremely toxic.
The optical system of the laser is susceptible to damage from particulate getting burnt onto the lens which reduces the laser efficiency and on marking applications can effect the quality of the code.
Additionally particulate in the laser beam can refract/reflect the light which diffuses the beam (see animation opposite).
Marking applications on open containers are vulnerable to particulate settling in the container which contaminates the product being filled.