Particulate matter is classified by particle size (or rather: by aerodynamic diameter). Dust with a particle size of 10μm is respirable. These particles reach the bronchial tubes. Smaller particles are even more hazardous, as they may penetrate deeper into the lung. Very fine dust will penetrate into the alveoli and block them, posing an unnecessary health risk.
Laser processes often produce particles and aerosols smaller than 1μm. These particles are especially hazardous as they penetrate deep into the respiratory tract and should not be inhaled! Dependent on their chemical composition, they have other health-damaging effects.
According to new analyses, there is no threshold beneath of which health-damaging effects by dust exposition is impossible, but health risks rise linear with dust exposition. EC clean air plans allow a maximum particle concentration of 40-50μg/m³, whereas, by contrast, laser processes generate particle concentrations of sometimes 100μg/m³ and more.
|Aerosols – emission||Laser-beam removing of plastics||> 30mg/s||< 0.12µm|
|Welding metal||> 9mg/s|
|Cutting metal||> 100mg/s|
|Laser-beam removing of varnish||> 25mg/s||< 0.23µm|
|Particulate matter concentration||Cutting plastics||> 500µg/m³||< 1.7µm|
|Cutting metal||> 300µg/m³|
|Welding metal||> 2000µg/m³|
More detailed information is provided by the German Laser Zentrum Hannover by their database lasersafety (http://www.lzh.de/en/publications/laser_safety) As you can learn from the table above, the threshold of 50µg/m³ is often exceeded dramatically. In addition, the generated particles are small enough to penetrate deep into the respiratory tract. They will mostly reach the alveoli which will be blocked by this foreign material.