Advanced Industrial Hygiene

MOS 6301, Advanced Industrial Hygiene 1

Course Learning Outcomes for Unit VI Upon completion of this unit, students should be able to:

7. Recommend controls for industrial health hazards. 7.1 Calculate required flow rates based on hood design. 7.2 Compare and contrast available engineering controls for noise hazards. 7.3 Explain how to gauge the effectiveness of engineering controls.

Course/Unit Learning Outcomes

Learning Activity

7.1

Unit Lesson Chapter 8, pp. 159–185 Web Page: “Recommended Practices for Safety and Health Programs: Hazard

Prevention and Control” Presentation: Unit VI PowerPoint Unit VI Scholarly Activity

7.2

Unit Lesson Chapter 11, pp. 237–255 Web Page: “Recommended Practices for Safety and Health Programs: Hazard

Prevention and Control” Presentation: Unit VI PowerPoint Unit VI Scholarly Activity

7.3

Unit Lesson Chapter 1, pp. 13–16 Chapter 8, pp. 159–185 Web Page: “Recommended Practices for Safety and Health Programs: Hazard

Prevention and Control” Presentation: Unit VI PowerPoint Unit VI Scholarly Activity

Reading Assignment Chapter 1: Introduction to Industrial Hygiene, pp. 13–16 Chapter 8: Ventilation, pp. 159–185 Chapter 11: Noise, pp. 237–255 In order to access the following resources, click the links below. Occupational Safety and Health Administration. (2016). Recommended practices for safety and health

programs: Hazard prevention and control. Retrieved from https://www.osha.gov/shpguidelines/hazard-prevention.html

The PowerPoint presentation includes several examples of calculations similar to those you will be required to perform for this week’s assignment. Click here to review the Unit VI PowerPoint Presentation. Click here to download the PDF version of the presentation.

UNIT VI STUDY GUIDE

Workplace Controls for Health Hazards: Elimination/Substitution and Engineering Controls

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Unit Lesson Control The last tenet of industrial hygiene (IH) is control. Once you evaluate the health hazards in a workplace, you must identify the hazards where controls are required to reduce risk. This introduces two important terms that the industrial hygienist must understand, hazard and risk. Many publications you read will use the terms interchangeably. Even the textbook we are using for this class uses the term hazard in a manner that applies more readily to the term risk on page 13. However, hazard and risk are quite different terms. Hazard versus Risk A hazard is anything that has the potential to cause harm to an individual, the environment, or a workplace, and risk is an assessment of the probability that harm will occur and the severity that would be associated with that harm (Fuller, 2015). This means that each hazard that is identified in a workplace should be assessed for risk. When we recommend controls for the identified hazards, the controls are designed to reduce the risk associated with the hazards. A concept that is important in this process is residual risk. Residual risk is the risk that remains after you have implemented all feasible controls. You should remember that if a hazard is present in a workplace, there will always be some level of residual risk present. You cannot have a hazard present with zero risk. The task of the industrial hygienist is to reduce the residual risk associated with hazards to an acceptable level (OSHA, 1999). The question this should raise in your mind is, “what is an acceptable level of risk?” There is no specific answer to that question. Each industrial hygienist must make a determination of acceptable risk based on published guidelines and the internal policies of the company for which they work. You may think that the permissible exposure limits (PELs) established by the Occupational Safety and Health Administration (OSHA) represent an acceptable level of risk for exposures. However, as we discussed previously, many of the PELs are based on outdated scientific research and many have levels of risk that even OSHA does not consider an acceptable level. This is true because few occupational exposure limits (OELs) have been established in order to achieve a set level of risk (Wheeler, Park, Bailer, & Whittaker, 2015). OSHA must also consider the economic and technological feasibility when setting their OELs (Occupational Exposure to Respirable Crystalline Silica, 2016). So, what does this mean for industrial hygienists trying to evaluate health risks using sampling data? Traditionally, risk assessments have been performed using a tool like the risk assessment matrix seen below.

Outcomes Likelihood

Severity Rating

Health Very Likely

Likely Possible Unlikely Very Unlikely

5 4 3 2 1

5 Death or Permanent Total Disability

25 20 15 10 5

4 Permanent Partial Disability

20 16 12 8 4

3 Injury or Illness with Lost Workdays

15 12 9 6 3

2 Injury or Illness with No Lost Workdays

10 8 6 4 2

1 First Aid Only or No Treatment

5 4 3 2 1

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By estimating the probability of harm and the associated severity, the industrial hygienist can develop a semiquantitative risk-assessment result. As you can see, many risk assessment matrices are color coded to indicate the acceptability of the calculated risk. However, the color coding is not a regulatory result. In other words, whether you determine a resulting risk score is unacceptable (in red), acceptable (in green), or somewhere in between (orange or yellow) is a subjective decision. Most industrial hygienists would agree that a personal exposure that is very likely to occur and that can cause death or permanent total disability would be unacceptable and that a personal exposure that is very unlikely to occur and that would result in no treatment or only require first aid if it did occur would be acceptable. What about a personal exposure that is possible (but not likely) but could cause an illness that would result in the worker missing workdays? Would that be acceptable or unacceptable? At that level, the industrial hygienist would need to make a judgment call based on education about the work task, the workers involved in the task, and the potential outcomes of the exposure. In these cases, you may see different decisions about the acceptability of the risk for different industrial hygienists working for different companies. The information you can use to evaluate the risk associated with exposures at specific levels would include existing OELs and an understanding of the toxicological data for the compound(s). Remember, we discussed many of the toxicological principles in a prior unit. Knowing that one compound is much more acutely toxic than another compound, by reviewing data such as the Lethal Concentration 50%( LC50), Lowest Observed Adverse Effect Level (LOAEL), No Observed Adverse Effect Level (NOAEL), Immediately Dangerous to Life and Health (IDLH) concentrations, carcinogenicity, and mutagenicity, to name a few, may result in you deciding a risk-assessment result for that compound is unacceptable while the same assessment result for the second compound may be acceptable. After you determine that a sample result represents an unacceptable risk, you need to determine which controls to implement to reduce the risk. In this case, OSHA has established some clear requirements. OSHA requires the use of specific controls be implemented first (or show them to not be feasible) before other, less effective controls can be used. The list of controls that OSHA requires to be considered are commonly called the hierarchy of controls (OSHA, 2016). The categories of control methods in the hierarchy of controls from most effective to least effective are elimination/substitution, engineering controls, administrative and work practice controls, and personal protective equipment (PPE; OSHA, 2016). We will look at elimination/substitution and engineering controls in this unit and administrative and work-practice controls and PPE in the following unit.

(Centers for Disease Control and Prevention, 2015)

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Elimination and substitution controls are the most effective controls because they completely remove the hazard of concern from the workplace. By removing the hazard from the workplace, the risk associated with that hazard is also eliminated (reduced to zero; OSHA, 2016). The primary consideration for substituting an alternate chemical for the original hazard would be the risk level of the substitute chemical. Substitution is only effective in reducing risk if the use of the substitute chemical results in a lower health risk to workers than the original chemical. In order to determine if this is true, the industrial hygienist would have to perform a risk assessment for both compounds, including a review of toxicological data and perhaps sampling for both compounds in the workplace. An example of this approach would be if a work task used 100% formaldehyde for a disinfection process. Since formaldehyde is a known carcinogen, the risk is elevated. If you could find a chemical that has less potential for harm to workers in the area and it performed the required disinfection adequately, you could substitute the second chemical for formaldehyde. In practice, elimination/substitution can be quite difficult to complete because of requirements in the production process. For example, if your client requires arsine gas to produce computer chips, you could not substitute a nontoxic gas, such as nitrogen. The next most effective control method in the hierarchy of controls is engineering controls. These are not as effective as elimination and substitution because they do not remove the hazard from the work area. Instead, they are designed to reduce the workers’ exposures to the chemical (OSHA, 2016). Since the hazard is still present in the work area, some residual risk will remain. The most commonly used engineering control is ventilation. There are two basic types of ventilation systems: general dilution ventilation and local exhaust ventilation (Fuller, 2015). The textbook contains a detailed explanation of ventilation systems in Chapter 8. A general dilution ventilation system simply moves air. The concentration of chemicals in the area are reduced by bringing in fresh air from outside the area that does not contain any concentration of the chemical and mixing it with the contaminated air. Some systems will blow air from the work area to areas outside the work area instead. This type of system requires some type of air mover (a fan). The fan can be as simple as a box fan or as complex as a series of fans that pull air from outside the work area through the ceiling or the side walls of the building (Fuller, 2015). With this system, the air is typically not filtered or treated in any way. The air is simply moved from one area to another area, causing uncontaminated air to move into the work area and reduce the concentrations of contaminants in the area. Local exhaust ventilation (LEV) systems collect air in an area and move it through some type of treatment or filtration system or outside through air ducts (Fuller, 2015). The types of filters used or treatments employed vary depending on the compound(s). For example, particles can typically be collected on filters (or baghouses with cyclones) placed in the system. Some volatile organic compounds (VOCs) can be adsorbed onto activated carbon. Acidic aerosols can be passed through a neutralization system. In some cases, isolation boxes will be included as part of an LEV system. The combination of an isolation device and LEV system are commonly used in laboratory and medical settings. They are commonly called laboratory hoods or fume hoods (Fuller, 2015). If the industrial hygienist recommends a ventilation system, there must be some design work performed. The textbook shows some examples of the types of calculations that might be required for different types of ventilation systems. A PowerPoint presentation with more examples is also included for your review. The calculations are required to make sure the ventilation system design can effectively capture and move air to the point that employee exposures are reduced as much as is practical. Paying for the installation of a ventilation system and then discovering that personal exposures were not effectively reduced to an acceptable risk level can be rather frustrating! Engineering controls for physical hazards are typically much different than for chemical hazards. Ventilation systems are ineffective for reducing personal exposures to physical hazards such as noise and radiation. Engineering controls for physical hazards typically involve installing something to block the exposure before it reaches the employee. For noise, an effective engineering control is the installation of sound-deadening material between the noise source and the employee (Fuller, 2015). This can be hanging sound-deadening curtains or building an isolation box around the noise source using sound-deadening materials. The difficulty with implementing engineering controls for noise sources is that the sound-deadening materials must be effective for the primary octave bands of the noise. This may require sampling of the noise using special noise meters equipped with octave band analyzers. An example that most of you are probably familiar with for

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radiation is the installation of lead-lined walls in areas where X-ray machines are used, the lead in the walls blocks (absorbs) the X-rays to reduce the exposure to workers outside the room.

References Centers for Disease Control and Prevention. (2015). Hierarchy of controls [Graphic]. Retrieved from

https://www.cdc.gov/niosh/topics/hierarchy/images/HierarchyControls.jpg Fuller, T. P. (2015). Essentials of industrial hygiene. Itasca, IL: National Safety Council. Occupational Exposure to Respirable Crystalline Silica, 81 Fed. Reg. 16286 (March 25, 2016) (to be codified

at 29 C.F.R. pts. 1910, 1915, & 1926). Occupational Safety and Health Administration. (1999). Standard interpretations: Clarification of OSHA’s risk

assessment and approach for setting the asbestos PEL. Retrieved from https://www.osha.gov/laws- regs/standardinterpretations/1999-07-23

Occupational Safety and Health Administration. (2016). Recommended practices for safety and health

programs: Hazard prevention and control. Retrieved from https://www.osha.gov/shpguidelines/hazard-prevention.html

Wheeler, M. W., Park, R. M., Bailer, A. J., & Whittaker, C. (2015). Historical context and recent advances in

exposure-response estimation for deriving occupational exposure limits. Journal of Occupational and Environmental Hygiene, 12(Suppl. 1), S7–S17. Retrieved from https://doi.org/10.1080/15459624.2015.1076934

Suggested Reading In order to access the following resources, click the links below. The CSU Online Library contains many articles that relate to the Unit VI readings. The following are just a few of the related articles that can be found in the Academic Search Complete database: Local exhaust ventilation systems (LEVs) are commonly used in areas where portability is important. Surgical suites would be one example because of the need to move the LEV depending on where the contaminant generation occurs. The following article shows how the use of an LEV reduces exposure to both particulate and volatile organic compounds (VOCs) in a surgical operation. Lee, T., Soo, J.-C., LeBouf, R. F., Burns, D., Schwegler-Berry, D., Kashon, M., & Harper, M. (2018). Surgical

smoke control with local exhaust ventilation: Experimental study. Journal of Occupational and Environmental Hygiene, 15(4), 341–350. Retrieved from https://libraryresources.columbiasouthern.edu/login?url=http://search.ebscohost.com/login.aspx?direc t=true&db=a9h&AN=128834255&site=ehost-live&scope=site

Several variables must be considered when implementing a general dilution ventilation system. One of those variables is wind velocity. The following article demonstrates how changes in the designed velocity in a ventilation system can change the protection the ventilation can provide. Bennett, J., Marlow, D., Nourian, F., Breay, J., Feng, A., & Methner, M. (2018). Effect of ventilation velocity on

hexavalent chromium and isocyanate exposures in aircraft paint spraying. Journal of Occupational and Environmental Hygiene, 15(3), 167–181. Retrieved from https://libraryresources.columbiasouthern.edu/login?url=http://search.ebscohost.com/login.aspx?direc t=true&db=a9h&AN=128402085&site=ehost-live&scope=site

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There are multiple types of local exhaust ventilation (LEV) systems. The type you use is influenced by the operation. In some cases, it is better to use a downdraft type LEV. The following article evaluates a mobile downdraft LEV to determine how well it works at different flow rates. Lo, L.-M., Hocker, B., Steltz, A. E., Kremer, J., & Feng, H. A. (2017). Performance evaluation of mobile

downflow booths for reducing airborne particles in the workplace. Journal of Occupational and Environmental Hygiene, 14(11), 839–852. Retrieved from https://libraryresources.columbiasouthern.edu/login?url=http://search.ebscohost.com/login.aspx?direc t=true&db=a9h&AN=125963641&site=ehost-live&scope=site

The hierarchy of controls shows that elimination/substitution is the most effective control method for reducing risks associated with health hazards. However, elimination/substitution is not used as often as other control methods on the hierarchy of controls. The following article summarizes testing that was performed during oil and gas extraction activities. Toward the end of the article, you will see how these IH professionals recommended both elimination and substitution controls to reduce the risks during these activities. Esswein, E. J., Alexander-Scott, M., Snawder, J., & Breitenstein, M. (2018). Measurement of area and

personal breathing zone concentrations of diesel particulate matter (DPM) during oil and gas extraction operations, including hydraulic fracturing. Journal of Occupational and Environmental Hygiene, 15(1), 63–70. Retrieved from https://libraryresources.columbiasouthern.edu/login?url=http://search.ebscohost.com/login.aspx?direc t=true&db=a9h&AN=126995449&site=ehost-live&scope=site

Learning Activities (Nongraded) Nongraded Learning Activities are provided to aid students in their course of study. You do not have to submit them. If you have questions, contact your instructor for further guidance and information. OSHA considers ventilation to be one of the most important engineering controls. OSHA has devoted an entire section of its website to ventilation. Access the section at https://www.osha.gov/SLTC/ventilation/index.html. Explore the site to see what information you can find to assist you in recommending and implementing ventilation controls in a workplace.