We see it just about every day; heck, we even see it with safety people… not properly rolling, lifting, inserting, and holding their hearing protection as they insert them. But noise is a “chronic” hazard and thus far too many workplaces fail to respect it. Unfortunately, in the vast majority of projects, we have completed for clients, engineering controls was by far the best option. Even from a cost standpoint, the passive engineering option would have paid for itself within 5 years as it would have reduced the exposure(s) to below 80-dBA, which means no more HCP training, annual audiograms for hundreds of workers, no need for HPs, etc. Some validation monitoring ensures the passive engineering control maintains exposures below the OSHA Action Limit of 85-dBA. But, that passive engineering control will cost thousands of dollars, and there is no budget for it. So what do most businesses do? The old game of using PPE (horribly, I might add) to control a chronic hazard that no one cares about (by the time the consequences arrive, we’ll all be gone approach!). So using noise exposure, let’s discuss the Hierarchy of Controls and how they logically play a role in controlling a recognized, yet unrealized, hazard in the workplace.
Our first hazard/risk control MUST be engineering controls. And a “passive engineering” control is the best kind of engineering control, as they require no power, very little maintenance, and are often left alone by employees. In the case of noise, noise curtains/barriers/containment are a perfect example of passive engineering control. We identify the noise source(s) and simply surround them with acoustic curtains that will reduce employee exposure. These curtains/barriers/containment comes with an NRR of sorts, but it is a trained professional who specifies the necessary reduction of noise and specifies and oversees the installation of these curtains/barriers/containment. Granted, at some point, a human will need to work on the noise source (e.g., motors), and this will require them to break the seal of the curtains/barriers/containment system. So even a “passive engineering” control can (and will) be defeated by unknowing humans, thus why we need to have the next layer of protection… ADMINISTRATIVE CONTROLS in the form of training for these individuals, backed up by the annual noise monitoring to validate the controls, are still providing the necessary level of protection.
But in the spirit of this post, let’s discuss administrative controls as they would apply to a high noise area to reduce exposures. A typical administrative control for this high-noise area could be “job rotation,” where employees’ exposures are controlled by limiting the time they work in the area. Noise exposures are based on Time-Weighted Average, so using this as a control method is very simple. However, I encourage you to use a 3-dB exchange rather than OSHA’s antiquated 5-dB exchange and use 80-dBA as your target goal. For example, the noise exposure in the area, should the employee spend their full 8-hour work shift in the area, would exceed the PEL of 90-dBA. So rather than install the curtains/barriers/containment around the noise source that is causing this over-exposure potential or by requiring the employee(s) to wear hearing protection devices, we would simply limit the amount of time an employee can work in this area. But this approach is also open to significant errors and abuse by untrained/qualified professionals. The most common error we see is that crews changed to 12-hour shifts from the 8-hour shifts when this control was implemented, and thus the rotation schedule is causing overexposures. But we also see a lot of abuse within these administrative controls, such as workers like the job(s) within the high noise area better than the ones outside the area. They will strike deals with their co-workers that put them in the high noise area for the full shift (again, they do not recognize the chronic hazard of noise exposure). These administrative controls demand a very disciplined approach to safety management, and very few workplaces possess this level of discipline within their SMS to pull this off safely.
The last measure of safety for this high noise area and the one control method most often utilized is also the weakest of them all… Hearing Protection Devices. We get calls every year asking for help with noise (and we are NOT Industrial Hygienists!) because the company has an HP program and provides HPDs to everyone and yet they continue to suffering hearing loss cases. Most of the time, we find the employees are not properly donning their HPDs; heck, oftentimes, the safety team is not even donning their HPDs properly. But on an increasing basis, we are finding the facility has failed to perform the required “attenuation evaluation” on the HPDs they are offering. Of course, when an untrained person makes the purchasing decisions on which HPDs are being bought, you can bet $ overrides NRR. So even if the employees are properly donning their HPDs, the actual HPD is not providing ample protection, and thus we end up with overexposure.
As you can see, no single control method is perfect. Humans make mistakes- untrained/uneducated humans trying to manage a hazard can make a lot of mistakes and a lot of serious mistakes! This is why we like to use ALL THREE controls (engineering, administrative, and PPE) to build-in safety capacity so that when one control becomes weakened by human error (both the worker exposed and the person building the programs and making key decisions), the other controls can compensate and maintain exposures below the hazard level. For example, we install curtains/barriers/containment around the noise sources. Since these engineering controls are so effective, we do away with the job rotation, HPDs, and routine monitoring and auditing/inspecting of our controls. But within months of their installation, a worker breaks these barriers to work on the noise source (i.e., motor(s)). When he/she finishes their work, they do not properly replace the curtains/barriers/containment around the noise source, leading to an unrecognized overexposure situation. This is why we insist that for true control of this noise hazard, the employees still be in an HCP that includes training and the proper use of adequate HPDs. Maybe, we could end the annual audiograms and recoup serious cost savings within the HCP, but we still need those additional layers of protection to ensure the hazard is controlled.