Standardization of Cab Air Quality - Defining Dust - Part 2
There are different types of dust and different sizes of dust. These different types and sizes have very different potential health effects for workers. Activities generating dust include mining, quarrying, harvesting, woodworking, and manufacturing. Examples include some wood, coal, silica, cement, and grain dust, just to mention a few. Workplace dust diameters range from approximately 100µm (human hair) down to <0.1µm (nanoparticle).
I have spoken to many mining, industrial and agricultural equipment operators about dust. After a day in a “dusty” work environment, they inform me dust is not an issue as when they clean up at the end of the shift, they cough and blow their nose, and all the dust comes out onto the tissue’s all ok. This is an example of the size of the dust and our body doing what it is designed for. This dust is called Inhalable dust. The larger dust particles get into our mouth and nose and are trapped by the nasal hairs, mucus, etc., which we can blow out or cough up.
Types and sizes of dust
Dust breathed in by the workers may also have sizes that are small enough to go further into the respiratory system and cause damage. They are smaller and don’t get trapped in our nose/mouth. They make their way into our lungs' upper respiratory area or the lower respiratory area and are deposited in the gas exchange region. Those that get trapped/deposited in the upper respiratory area are called thoracic dust, and those that get deposited into the lungs are called respirable dust. Long-term exposure to this dust can result in occupational illness and disease for the worker if they are not effectively controlled.
As we consider standards for operator enclosures (e.g. for mobile equipment), it is essential to ensure the engineering controls recommended by the standard are effective in preventing dust from entering and remaining in the cab.