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

Hazards	Engineering controls	Administrative Controls
Worker-material interfaces
Repetitive ergonomic hazards - extremities	Repetition-mechanical aids, automation, distribution of tasks across the shift and the workforce Force – decrease weight of tools/containers, optimize handles, torque control devices Postures – locate work for mechanical advantage	More frequent or longer rest breaks, limit overtime, varying work tasks, rotation of workers between less and more ergonomically stressful jobs
Manual materials handling – backs	Same as above	Same as above
Vibration	Whole body – relocate worker away from vibration, mechanically isolate vibration, use vibration-isolating seats in vehicles Hand-arm – use anti-vibration tools	Hand-arm-removal from work for significantly affected workers
Mechanical energy – direct injuries	Guards, interlocks, proper lighting, non-skid floors	None
The physical work environment
Hot environments	Air conditioning, increase air movement, insulate and shield hot surfaces, decrease air humidity, shade work area, mechanize heavy work	Use recommended work/rest cycles, work during cool hours of the day, provide cool rest areas, use more workers for a given job, rotation of workers between less and more physically stressful jobs, provide fluids for cooling and hydration
Cold environments	Enclose and heat work area	Use recommended work/rest cycles, provide appropriate clothing, provide shelter for break, provide fluids for warming and hydration
High-pressure environments	Engineer a “shirtsleeve” environment which avoids high-pressure work	Work under no decompression guidelines/tables. Adhere to recommended decompression guidelines
Low-pressure environments	Work remotely at low altitude	Wait 12-48 hours after diving to fly, schedule time for acclimation when working at altitude
Shift work	Automate processes to reduce the number of workers/shift	Rotate shifts forward, get worker input for desires of time off and shift design
Energy and electromagnetic radiation
Ionizing radiation	Shielding, interlocks, increase worker distance to source, warning signs, enclose radionuclides	Worker removal if dose limit reached, minimize exposure times, use radionucides only in designated areas using safe handling techniques, limited personnel access
Ultraviolet radiation	Enclosure, opaque shielding and/or tinted viewing windows, interlocks, increase worker distance to source, non-reflective surfaces, warning signs	Minimize exposure times, limited personnel access
Visible light and infrared radiation	Enclosure, shielding, interlocks, increase worker distance to source, non-reflective surfaces, warning signs	Limited personnel access
Laser radiation	Enclosure, interlocks, non-reflective surfaces, warning signs	Limited personnel access
Microwave, radiofrequency (MW/RF) and extremely low-frequency (ELF) radiation	MW/RF – Wire mesh enclosure, interlocks, increase worker distance to source, warning signs ELF – Increase worker distance to source	MW/RF – Limited personnel access
Noise	Enclose sources, warning signs	Limited personnel access
Electric power and electrocution injuries	Interlocks, warning signs	Limited personnel access

Table 2 – Commonly used personal protective equipment for physical hazard

	Equipment type		Hazard category	Specific hazard
	Helmet		Direct injuries	(1) Falling objects (2) Low clearances/”bump hazards”
	Safety glasses		(1) Direct injuries	(1) Flying objects (2) Sparks
			(1) Lasers Direct injury	Retinal burns (1) Flying objects (2) Molten metal, sparks
	Welding helmet/goggles		(1) Direct injury	(1) Flying objects (2) Molten metal, sparks
			(2) Ultraviolet radiation	Skin/conjunctival burns
	Earplugs/earmuffs		Noise	Noise
	Fall protection systems-safety belt, body harness, lines and/or other hardware		Direct injury	Falls
	Respirators		Ionizing radiation	a-Emitters: internal contamination
	Clothing
		Leather	Heat	Burns
		Aluminized	Heat	Heat stroke, burns
		Lead	Ionizing radiation	g - Emitter, X-rays
		Fire-resistant	Direct injury	Burns
		Insulating	Cold	Hypothermia
		Disposable	Ionizing radiation	a - Emitter: external contamination
Gloves
		Leather	Direct injury	Abrasions, lacerations
		Rubber	Electric injury	Lacerations
		Metal mesh	Direct injury	Lacerations
		Anti-vibration	Vibration	Vibration
Footwear
		Steel toe	Direct injury	Falling objects
		“Traction sole”	Direct injury	Slips, trips, falls
		Rubber	Electric energy	Electrocution

Table 1 – Engineering and administrative controls for physical hazards

Worker-material interfaces

Energy and electromagnetic radiation

Table 2 – Commonly used personal protective equipment for physical hazard