Table 2. Identification of Candidate Measures Which Could Control Worker Exposures to Air Contaminants
Job Title: Target Air Contaminant Exposures (follow up from Step 1 Exposure Hazard Assessment) (1)
(2) Potential Exposure Source Exposure Control Measure (3) Key Objectives Column Descriptions
hazard assessment is to identify jobs where measures to control exposure of workers to air contaminants need improvement. Once the need has been established, a variety of guidance can be applied to plan and implement improved exposure control measures. A guidance model for selecting
exposure control measures which has been used for many years by the industrial hygiene profession is the “Hierarchy of Exposure Controls.” Te term “hierarchy” connotes a series of systematic groupings in graded order. A typical example is the following ranking published by the National Institute for Occupational Safety and Health (NIOSH): Elimination is seen as the most
effective control. Elimination includes design of a process to eliminate hazards. For example, a shut off valve that can only be accessed by climb- ing a ladder can be moved to provide access at ground level in order to eliminate a fall hazard. Elimina- tion tends to be the most difficult to implement in an existing process. In the design or development stage, elimination of hazards may be simple and inexpensive to implement. How- ever, for an existing process, major process or equipment changes may be required to eliminate a hazard. Substitution can be used to
replace the hazard with alternative methods or materials, thereby reduc- ing the risk of harm from hazards. For example, substituting less hazard- ous materials or materials with a lower vapor pressure to limit evapora- tion may reduce hazardous inhala- tion exposure. For existing processes, substitution may require equipment or process modification. Engineering controls can be used to isolate people from the hazard.
32 | MODERN CASTING July 2016
Barriers or guards can be used for mechanical hazards. Local exhaust ventilation can be used to remove airborne contaminants from workers’ breathing zones. Engineering controls are preferred over administrative and personal protective equipment (PPE) because they are designed to control the hazard at the source, before it comes in contact with the worker, and are typically independent of worker intervention to achieve protection. Te initial cost of engineering controls can be higher than the cost of admin- istrative controls or PPE, but over the longer term, operating costs are frequently lower. Administrative controls are used
to change the way people work and include a broad range of control measures such as training, job rota- tion, work procedures, warning signs, temporary barricades and inspec- tions. Administrative controls can be relatively inexpensive to establish, but require a high level of effort to sustain. PPE such as safety eyewear, respira-
tors, hard hats, aluminized clothing, gloves and safety toed shoes can protect the worker but require the greatest amount of worker intervention to be effective. PPE is also often subject to fit problems and maintenance issues. From the standpoint of the hierarchy, PPE is considered the least desirable control. Nevertheless it is one of the most com- mon control techniques employed and there are good reasons for that. All versions of the hierarchy of
controls are based on assumptions and generalizations about effectiveness and reliability. Te bases of the hierarchies are that control methods at the top or preferred end of the hierarchy are potentially more effective and protec- tive than those at the bottom. Mea- sures that require human intervention,
such as warnings, training, or PPE, are seen as less effective than measures that do not require human interven- tion. Measures that can be defeated or circumvented are less preferable to those that are integral. Selecting risk reduction measures in the order of preference suggested by the hierarchy is expected to lead to more effective controls and implementation of inher- ently safer systems, where the risk of illness or injury is minimized. OSHA requires industry to
work through the development and implementation of exposure control measures to achieve effective and reliable performance from them “to the extent feasible.” If feasibility turns out to be limited, PPE is necessitated going forward. In a dynamic foundry production environment, an exposure control development and implemen- tation program must be carefully managed and monitored. Until that is established, PPE stands as the primary assurance of exposure control, not as a recourse measure at the bottom of the hierarchy rankings. Although these generalizations can
form the basis of a useful control strat- egy, they are not infallible and must be applied in context. To begin with, the exposure and risk must be understood. Does the risk warrant control? In some cases, the risk may not require control and in other cases properly addressing the risk may call for redundant con- trols, especially where the likelihood and potential consequence of control failure are significant. In addition, the sources of exposure must be identified and understood if control measures are to be effective and reliable. Controls will not be effective if applied to the wrong exposure source or causal condition. Existing control measures should be evaluated to confirm that
Page 1 |
Page 2 |
Page 3 |
Page 4 |
Page 5 |
Page 6 |
Page 7 |
Page 8 |
Page 9 |
Page 10 |
Page 11 |
Page 12 |
Page 13 |
Page 14 |
Page 15 |
Page 16 |
Page 17 |
Page 18 |
Page 19 |
Page 20 |
Page 21 |
Page 22 |
Page 23 |
Page 24 |
Page 25 |
Page 26 |
Page 27 |
Page 28 |
Page 29 |
Page 30 |
Page 31 |
Page 32 |
Page 33 |
Page 34 |
Page 35 |
Page 36 |
Page 37 |
Page 38 |
Page 39 |
Page 40 |
Page 41 |
Page 42 |
Page 43 |
Page 44 |
Page 45 |
Page 46 |
Page 47 |
Page 48 |
Page 49 |
Page 50 |
Page 51 |
Page 52 |
Page 53 |
Page 54 |
Page 55 |
Page 56 |
Page 57 |
Page 58 |
Page 59 |
Page 60