Respirable Crystalline Silica dust and the lungs – size matters

Remember we talked about dust particles being of different sizes? We can measure these particles and categorise them by size into what are called “fractions”.

Below you can see the size of the different fractions of RCS dust – and how small they are compared to a grain of salt.

The body’s natural defences are able to eliminate and clear much of the inhalable dust inhaled. That’s why it can make you cough and sneeze, as the body clears the particles.

However, dust smaller than 10 microns (which is ¹/₁₀₀^th of a mm) make up the ‘respirable fraction’, which means they’re small enough to pass the body’s defences and penetrate deep into the lungs.

In the short term, this dust doesn’t cause a problem. However, exposure to high levels of the respirable fraction over time (we’re talking years), can irritate the cells in the lungs where oxygen and carbon dioxide are exchanged. This causes permanent damage, which makes the lungs less effective, a condition you have probably heard of known as silicosis. There may also be a higher risk of developing lung cancer.