Inhalable, Respirable and Visible Dusts: Know The Difference

Visible Dusts – as the name implies – are what you can visibly see.

The particle sizes covered in this range will vary according to a few factors such as the colour of the mineral or metal and lighting but generally the visible component of visible dust clouds will be of a larger particle size and even potentially not inhalable.  Where there is visible dust however, there is likely to be inhalable and respirable dust. 

 

Inhalable Dust is a further classification – It is the component that will enter the Nose & Mouth During Normal Breathing. 

 

Respirable Dust is a further classification of inhalable dust and consists of the fraction between “Zero” and 18 µm.

This fraction is the most harmful as they are dusts that are able to reach lower bronchioles & alveolar regions of the lung.

A good portion passes through the sinuses (the human body’s only dust filter) and because they can penetrate so deeply they are more difficult for the body to remove. This fraction is a “silent killer” as it’s usually less visible and may pass through incorrectly sized respiration filters – so you may not be aware a dust is present until its too late.   

Due to their small size gravity doesn’t work very well on this fraction so they resist dropping out of the air and linger in the area unless blown away or extracted. Even slight static charges move them around. Larger water droplets generally repel them instead of adhering to them and so simple dust suppression strategies may be ineffective.  

It is important to note the smaller the particle size the more respirable it is.