Consistent exposure to respirable crystalline silica for foundry workers is cause for concern as inhaling this toxic dust can cause severe and fatal illnesses. Due to the type of work that is done by foundry workers, complete elimination of silica dust would be impossible. For this reason, employees and managers must understand exposure risks, as well as the importance of monitoring for silica dust in the air. This often can be completed through the creation and implementation of an industrial hygiene program. An industrial hygiene program can help to identify and monitor employees who are potentially at risk, and with means available, can also assist in helping to control silica dust exposure levels for each employee.
Understanding Silica Dust Exposure Risks
Developing a silica related disease is directly related to the concentration of crystalline silica that is found in the dust that comes from the material being worked with. A higher risk is often associated with materials that contain more crystalline silica; however, it is a mistake to assume that overexposure is nonexistent in materials that contain less crystalline silica. Depending on the work process, enough silica dust can still be produced by these materials to cause exposure levels that are unsafe for foundry workers.
In some circumstances it may be simple to identify where silica exposures occur, such as being able to clearly see dust residue, but there are several other circumstances where exposures are more infrequent or less obvious that cause these processes to be overlooked. For example, sand casting operations present more opportunities for silica exposures than that of investment casting, permanent molding, and centrifugal casting operations.
While sand casting may be deemed as having more exposure opportunities, it does not mean that the other three operations never present exposure levels that can cause serious health issues for workers. Thoroughly analyzing exposure risk includes creating an inventory of dust producing processes, as well as how frequently, and the duration of time it takes for workers to complete these processes.
What Makes Monitoring So Important?
While each employee may be exposed to respirable crystalline silica, the amount that is actually breathed is not the same for every foundry worker. A great deal of the exposure level relates to the type of work that the employee is completing, as well as how long the employee is working in that particular area. The average concentration of respirable crystalline silica dust that is found in the breathing zone, along with the silica content found in that breathing zone, is referred to as the time-weighted average (TWA) exposure. Measuring TWA silica exposure should be the top priority of any silica dust management program as this sampling gives greater insight as to where efforts for exposure control should be allocated on the basis of the potential health risks.
TWA exposure information can be found and collected through the use of measurement instruments that can be worn by each foundry worker while performing their specified jobs. The information that these instruments provide allows foundry managers to see specific data in order to decide what control measures should be implemented for each employee and area of work. Monitoring the air for respirable silica dust is a vital part of protecting the health of foundry employees for the following reasons:
- Helps to determine which employees are in need of protection and just how much protection will be necessary
- Helps to assess whether control efforts have been, or are remaining, effective
- Helps to evaluate if there should be changes made to work practices to help reduce exposure
- Above all, air monitoring helps foundries comply with OSHA regulations, specifically OSHA’s updated standard, regarding respirable crystalline silica dust