May 24 , 2002

Protecting Your Workforce Through Engineering, Administrative and Personal Protection Equipment (PPE) Controls

By Peter H. Wald, MD, MPH
Board-Certified, Occupational Medicine, Medical Toxicology, Internal Medicine
Principal, WorkCare

An Excerpt from Physical and Biological Hazards of the Workplace

Substitution of less dangerous equipment or agents is the best protection from hazards, because it totally removes any chance of exposure.  However, substitution is often not possible; therefore, worker protection from physical hazards generally focuses on engineering controls.  Engineering and administrative controls for physical hazards are summarized in Table 1.  Often these controls involve isolation or shielding from the hazard.  The most effective isolation involves physically restricting an individual from a hazard area by fencing off the area whenever the hazard is present.  Interlocks that inactivate the equipment when the exclusion area is entered are often used to further enhance physical barriers.  Alternatively, the hazard can be “locked out” when a worker is present in an area that would become hazardous if the equipment were energized.  This process of excluding maintenance workers from hazardous areas has been institutionalized in the OSHA Lock-Out, Tag-Out (LOTO) Standard (Code of Federal Regulations [CFR] 1910.147).

Another way to protect workers is to specifically shield them from the hazard.  In some cases, an individual piece of equipment can be shielded to prevent exposure.  With some higher-energy hazards, such as ionizing radiation shielding may be needed in addition to isolation of the equipment.  In special cases where it is not practical to shield the hazard (e.g. cold, low pressure), individual workers can be shielded with personal protective equipment, such as jackets or environment suits.  In addition, it is sometimes possible to alter the process so as to decrease exposure.  This is often the case with hazards affecting the worker-material interface, where engineering design is often inadequate.  Personal protective equipment can also be used as an adjunct to engineering controls.  Table 2 also contains a summary of the most common personal protective equipment used for physical hazards.

The final strategy for hazard control is the use of administrative controls.  These controls are implemented when exposures cannot be controlled to acceptable levels with substitution, engineering controls, or personal protective equipment.  Administrative measures can be instituted to either rotate workers through different jobs to prevent repetitive motion injuries, or to remove workers from ionizing radiation exposure once a predetermined exposure level is reached.  Although this is not the preferred method of hazard control, it can be effective in some circumstances.  Administrative controls are also reviewed in Table 1.

The best way to determine what hazards are present in a specific workplace is to go to the site and walk through the manufacturing or service process.  There are some significant measurement issues that need to be addressed by an appropriate health professional.  Although larger employers will undoubtedly have such a person on staff, at the majority of smaller work sites, no such person will be available.

If you are unfamiliar with the measurement technology, make sure that you (or the employer) retain someone who knows how to do an exposure assessment.  Inaccurate measurements will invalidate the entire process of a prevention program.  There are, of course, a number of physical hazards that do not require special measuring and can be handled quite nicely with relatively low-cost safety programs.

Finally, remember that the human being is a biological system.  For a given exposure, different people will respond differently because of interindividual variation.  Most workplace standards are designed with a safety factor to protect against overexposure related to this variation (and to account for any knowledge gaps).  In addition, however, a worker's perception of the hazard must also be taken into account.  Some workers may have an exaggerated response to a non-existent or low-threat hazard, whereas others may not respond appropriately to a series hazard with which they have “grown comfortable".  The challenge in assessing and communicating the relative danger entailed by the hazard is to strike the right balance between these two competing tendencies.

Table 1 – Engineering and administrative controls for physical hazards

Table 2 – Commonly used personal protective equipment for physical hazard