Step 1. Establish an Exposure Control Baseline Action
Conduct an industrial hygiene risk analysis for exposure to air contaminants.
Identify exposure control measures in current use at the foundry in the categories of process, work practices, ventilation and housekeeping.
Evaluate the performance status of these control measures and restore them, as necessary, to their original design.
Conduct baseline exposure sampling at a time when all of the current exposure controls are in their base- line condition. Use the sampling results to set priori- ties for needed improvements in exposure control.
Notes
A thorough investigation of potential air contaminant sources should include review of the Hygiene Guide Series, published by AFS. Sampling should cross all potentially exposed job categories and include repeti- tive sampling as needed to improve the confidence level of the data.
When one considers exposure controls for air contaminants, ventilation systems and housekeeping immediately come to mind. The review of process considerations and work practices, which can prevent air contaminants from being created, should identify more control measures. Any opera- tional or maintenance procedure that reduces the occurrence of process upsets or equipment failures that result in fugitive air contamination should be acknowledged as a control measure.
There is often a temptation to upgrade design of control measures during this step. Although design improvements may ultimately be warranted, the task at hand is solely to quantify the current expo- sure protection capability.
The work shifts chosen for baseline study should be representative of normal production in the en- tire foundry. It is unnecessary to set either maximum or worst case scenarios for the baseline test. The sampling personnel should closely monitor baseline sampling to comprehend the situations which produce the sampling results.
Step 2. Determine the Root Causes of Exposure Action
Solicit input of workers, supervisors, individuals who gather samples, and other foundry staff.
As needed, conduct diagnostic sampling using real-time and segmental sampling methods.
Prioritize those root causes responsible for the majority of a worker’s exposure.
Conduct baseline exposure sampling when all of the current exposure controls are in their baseline condi- tion. Use the sampling results to set priorities for needed improvements in exposure control.
Notes
In particular, workers and supervisors know the scope of activities of their jobs, placing them in a good position to help identify potential exposure issues.
Real-time measurements of indicator air contaminants such as particulate matter can be employed to shed light on the presence of air contaminants for which no real-time sampling instruments are available. Either simultaneous video recording or note taking can be used to correlate real-time samples to recorded air contaminant levels.
There is often a temptation to upgrade design of control measures during this step. Although design improvements may ultimately be warranted, the task at hand is solely to quantify the current expo- sure protection capability.
Root causes are often recognized in real-time data by the “spikes” or periods of elevated readings they generate over and above the normal baseline. A high baseline of exposure, on the other hand, can signal ventilation stagnation in the workplace, which can itself be a root cause of exposure.
Step 3. Define and Evaluate Exposure Control Options Action
Analyze ways to attack root causes by changes to: 1) Process operations 2) Work practices 3) Ventilation 4) Housekeeping.
Solicit input in the process of identifying control options from the following sources at the foundry: 1) Workers and supervisors
2) Plant engineers and maintenance staff 3) Safety and health staff.
Seek additional input from other foundries, published case histories and industry manuals.
Use demonstrations as needed to determine the feasibility and effectiveness of candidate control measures.
Apart from the prerequisite need to achieve effectiveness in protect- ing workers from exposure, a candidate control measure must meet the following requirements to be considered feasible: 1) Prevent creation of new safety and health hazards 2) Assure the capability to produce quality castings in a timely manner 3) Gain the acceptance of workers.
50 | MODERN CASTING March 2013
The AFS has available a series of publications which address control measures for air contaminants. They can be acquired by accessing the AFS website.
Demonstrations can generate the most useful information when they are carried out under controlled conditions and scheduled when processes can be operated with no other operations underway to cross-contaminate the work area.
These three constants in any workplace determination are sometimes called “the pillars,” because they support all other feasibility determinations.
Notes
At the top of the hierarchy of control measures are methods that prevent air contamination from occurring (i.e., process operations and work practices). Ventilation and housekeeping occupy a lower tier of control because they must pursue fugitive emissions.
Many foundry staff who are familiar with potential air contaminant hazards already have ideas on how to address them. Experience has shown that many ideas for sustainable methods come from such individuals.
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