Know the Hazard

What’s the Risk?

A worker’s chance of becoming ill from exposure to silica dust depends on the tasks performed, the amount of dust they are exposed to, and the frequency of the exposures.  Each exposure to silica adds into the total load of silica in the lungs – in other words, each exposure adds to the lung damage.   

Health professionals express the total silica dose one person accumulates over time as  “mg/m3 years," usually calculated as an average exposure each year in mg/m3 multiplied by the number of years with that exposure, or by an estimated average for each year. As the total dose increases, so does the likelihood, or the risk, for developing silicosis, lung cancer, or chronic obstructive pulmonary disease (COPD).   Some workers become ill after many years of low exposure levels, while other workers who perform less frequent but high exposure tasks can become ill with a lower cumulative exposure.  Why?  Because a high exposure to silica dust overwhelms the lungs’ defenses and most of the dust settles deep into the lungs where it does the most damage. 

Researchers have developed estimates of the total dose likely to cause disease.  For example:

These very general estimates do not take into account individual susceptibility or other exposures at work that add onto the injury caused by silica and lead to disease at an earlier age.   

It is important to remember that repeated exposures to silica add up to a total dose that can cause serious lung disease.   The kinds of exposures we see in high exposure tasks, such as sandblasting and tuckpointing, over time can give a worker enough exposure to put him or her at serious risk for a silica-related illness. 

To learn more about the risk….