DEPARTMENTS
CONTROLS
D. JEFF BURTON, MS, PE, FAIHA (former CIH and CSP, VS), is an industrial hygiene engineer with broad experience in ventilation used for emission and exposure control. He is an adjunct faculty member at the Rocky Mountain Center for Occupational and Environmental Health at the University of Utah in Salt Lake City.
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Controls in Non-Industrial Environments
The OEHS Professional’s Role, Part 1
BY D. JEFF BURTON
Determining and applying appropriate hazard and exposure controls are among an OEHS professional’s main responsibilities. As the pandemic retreats and everyone returns to work and school, such controls will become even more important. We have a responsibility to choose controls that are feasible; compatible with the employee, process, and task; and financially attainable.
The types of control we choose typically depend on regulatory requirements, the nature of the hazard, the way the hazard affects the employee, and costs. We should also select controls that do not materially interfere with normal operations or compromise the safety of workers performing routine maintenance.
When implementing controls, OEHS professionals usually work with others, including managers and personnel in the facilities engineering and maintenance departments. In many cases, these professionals rely on us for guidance, cost estimates, and design assistance. We are also often involved in the review and commissioning of emission and exposure controls during design, installation, operation, and maintenance.
TYPES OF CONTROLS OEHS professionals should recognize five fundamental assumptions about controls. First, all hazards can be controlled to some degree and by some method; second, alternative approaches to control usually exist; third, more than one control is sometimes useful or required; fourth, some control methods are more cost-effective than others; and finally, incomplete control of the hazard may require us to augment our control strategies.
The three traditional approaches used to control emissions and occupant exposures are administrative controls, engineering controls, and personal protective equipment. Administrative controls include management involvement in health and safety issues, training of employees, rotation of employees, air sampling, biological sampling, medical surveillance, medical exams, and so forth. PPE includes gloves, aprons, rubberized clothing, hardhats, and respirators.
There are several kinds of engineering controls. Source modification involves changing the source of a hazard to make it less hazardous—for example, by wetting a surface to reduce dust particles, lowering the temperature of liquids to reduce off-gassing and vaporization, and capping open containers to reduce evaporation. Substitution is the use of a less hazardous material, piece of equipment, or process in place of a more hazardous one—for example, soap and water instead of solvents and automated equipment instead of manually operated equipment. An example of a process change is dipping a material in paint instead of applying the paint by spraying. Ventilation can be general exhaust, which is the dilution of air contaminants; or local exhaust, which is the removal of air contaminants using location-specific equipment. Finally, isolation separates employees from hazards through the use of control rooms, the placement of barriers between employees and hazardous operations, and the use of ventilated storage cabinets for chemicals or isolation booths and supplied-air ventilation islands for certain processes.
APPLICATION OF CONTROLS Applying emission or exposure controls is more difficult and expensive after an operation, process, or space configuration has been installed or constructed. Therefore, we should insist on being involved from the very beginning of any project where emissions or exposures are likely to occur, especially during design.
Design criteria found in good occupational health control programs usually have many requirements for OEHS professionals. We are expected to meet all applicable codes, regulations, and standards; provide useful OEHS input; and build processes to be as enclosed as possible, or to be remote from employees. We are expected to attempt to maintain employee exposures as low as possible (not just meet PELs); use low-hazard materials and processes when these options exist; make employee safety and health a major objective; and make process equipment as maintenance-free as possible. We are also typically asked to use automated systems as much as possible; obtain reviews of proposed plans and specifications by everyone with a stake in the outcome; and involve experts—for example, HVAC engineers for ventilation—as they’re needed and available.
Once a potential hazard has been anticipated, identified, or recognized, a team that includes OEHS professionals and personnel from facilities engineering, maintenance, and operations should generate a database of relevant information and a controls application plan. The plan should characterize the hazard, the sources of emission and exposure, the workers’ involvement with those sources, and air movement in the work area. Using this plan, the team should identify all available alternative controls; indicate which controls are the most effective, considering compliance requirements, costs, and ethics; implement the controls; and follow up with testing and maintenance.
We should insist on being involved from the very beginning of any project where emissions or exposures are likely to occur.
CONTROLS IN NON-INDUSTRIAL ENVIRONMENTS In its infancy, industrial hygiene concentrated on the control of emissions and exposures to blue-collar workers, such as those employed at industrial and production plants. Some OEHS professionals still focus on traditional hazards like silica and coal dust in mines, solvents and acid mists in manufacturing facilities, and heavy metals in smelters and foundries. In recent decades, the profession has recognized that white-collar workers—those who work in commercial establishments like stores and warehouses or in office, classroom, or medical environments—are also potentially exposed to airborne hazards. Exposures to white-collar workers can include chemicals emitted from building materials such as formaldehyde in pressed-wood products, carbon monoxide from fuel-burning heaters and furnaces, mold spores, bacteria, viruses, and chemicals used in maintenance and cleaning operations. Today, the control of airborne hazards in white-collar working environments has become as important for OEHS professionals as our traditional work in industrial facilities.
In non-industrial environments, two primary controls are commonly used: emission source controls and dilution ventilation.
There are several approaches to source control in office buildings, commercial establishments, schools, medical facilities, and other employee occupancies where exposure problems exist. For example, we can use, specify, or install equipment, materials, and furnishings that have low emissions or toxicity, low potential for causing irritation, and high thresholds for odor detection. Some materials significantly increase emissions when temperature or humidity rise and are therefore more likely to cause IAQ problems; we can choose alternative materials. Maintenance-free materials are less likely to become emitters, and materials that can be cleaned with water are less likely to become sources of IAQ complaints. We can choose suppliers and manufacturers that have conducted emission testing or offer IAQ-related information such as testing results. Without this information, it is difficult to attain good IAQ through source control. Finally, we can choose materials that have been “aged” or “aired out” prior to installation or occupancy. Airing-out materials allows the initial “burst” of emissions to occur before occupants are exposed. For example, carpet can be rolled out in a warehouse for several days or weeks before installation.
Ventilation is a widely used and time-tested approach to emission and exposure control. Almost every building employs some type of ventilation to promote or protect the comfort and health of its occupants. Types of ventilation include HVAC, which mechanically provides clean, tempered, or outside fresh air for comfort and health; general exhaust, which removes and replaces contaminated air before chemical concentrations reach unacceptable levels; local supply or supplied-air island, which provides clean, fresh air at a specific location for cooling, exclusion of contaminated air, or replacement of exhausted air; natural ventilation, which uses wind or temperature differences to induce airflow through the building and dilute air contaminants; and make-up air ventilation, which replaces air that is removed or exhausted.
VENTILATION EXAMPLE For a constant emission source, perfect air mixing in the space, and a constant airflow, the following relationship describes the resulting equilibrium concentration of air contaminants in a ventilated space such as a room, building, or chamber:
In this equation, q is the emission rate of the contaminant, C is its concentration in air, and Q is the ventilation rate in the same units as q.
For example, suppose a carpet installer reports, “For the first week, the carpet adhesive we use may emit a little toluene, at a rate of about 0.005 cubic feet per minute per 1,000 square feet of carpet.” That doesn’t sound like much, but if 150 square feet of new carpet have been installed in an office and you want to maintain indoor air concentrations below 2 ppm—which is well below the Threshold Limit Value of 20 ppm and just below a reported odor threshold for toluene—then the required dilution ventilation rate (Q = q/C) would be
or 375 cfm. So, for about a week after installation, you would want to provide at least 375 cfm of fresh outside dilution air to keep occupants safe and satisfied.
In the second part of this article, we will explore emission and exposure controls in industrial environments.

RESOURCES
AIHA: Industrial Hygiene Workbook, 6th ed., chapters 11–22 (July 2016).
AIHA: The Occupational Environment: Its Evaluation, Control and Management, 3rd ed., sections 2, 6, and 7 (October 2016).
National Safety Council: Fundamentals of Industrial Hygiene, 6th ed. (2012).
Wiley: Patty’s Industrial Hygiene, 7th ed., vol. 2, parts 4 and 7 (2021).