Advanced Industrial Hygiene

MOS 6301, Advanced Industrial Hygiene 1

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

4. Assess methods for performing industrial hygiene workplace analysis. 4.1 Summarize information from published sampling/analytical methods. 4.2 Calculate minimum required sampling times based on chosen sampling/analytical methods. 4.3 Describe industrial hygiene sampling processes.

Course/Unit Learning Outcomes

Learning Activity

4.1

Unit Lesson Chapter 6, pp. 119–133 Chapter 7, pp. 144–154 Chapter 11, pp. 248–250 Chapter 13, pp. 301–309 Presentation: Unit III PowerPoint Unit III Scholarly Activity

4.2

Unit Lesson Chapter 6, pp. 119–133 Chapter 7, pp. 144–154 Chapter 11, pp. 248–250 Chapter 13, pp. 301–309 Presentation: Unit III PowerPoint Unit III Scholarly Activity

4.3

Unit Lesson Chapter 6, pp. 119–133 Chapter 7, pp. 144–154 Chapter 11, pp. 248–250 Chapter 13, pp. 301–309 Presentation: Unit III PowerPoint Unit III Scholarly Activity

Reading Assignment Chapter 6: Gases and Vapors, pp. 119–133 Chapter 7: Aerosols, pp. 144–154 Chapter 11: Noise, pp. 248–250 Chapter 13: Thermal Stressors, pp. 301–309 In order to access the following resources, click the links below. The presentation contains images of equipment that was discussed in the lesson. Reviewing the presentation may provide a better understanding of the material in the lesson, especially if you have never performed IH sampling before. The PowerPoint presentation also contains examples of calculations that you might be required to perform in the unit assignment. Click here to review the Unit III PowerPoint Presentation. Click here to download the PDF version of the presentation.

UNIT III STUDY GUIDE

Evaluating Personal Exposures in a Workplace

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Unit Lesson After understanding how to anticipate and recognize hazards, the industrial hygienist must decide how to evaluate the risks associated with the identified hazards. This is the task that most workers associate with the field of IH. Many workers can remember when an industrial hygienist showed up at the worksite and required certain employees to wear pumps and other devices for the entire work shift. Even though the sampling is being performed to decrease employees’ health risks, this is also the task that many workers will object to because they view the sampling devices as being intrusive and difficult to wear. In many cases, the most difficult job the industrial hygienist has is to convince workers of the benefits of wearing a sampling device for their work shift. In this unit, we will look at the different ways IH sampling can be performed and how to make sure the data you produce is accurate and precise, in other words useful. IH Sampling Basics The essence of IH sampling for chemical hazards is passing a known volume of air through some media to remove the chemical of interest from the air, thus, collecting it on the media. The media are then sent to a laboratory where it is removed from the collection media and analyzed to determine the quantity of the chemical that was collected. The air concentration can then be determined by dividing the quantity of the chemical that was collected by the volume of air that was pulled through the media (Fuller, 2015). That sounds simple enough, right? What you must consider is that the results you get from sampling for exposures in a workplace will rarely be equal to the actual exposures that were present. Why? Because errors can enter into the process virtually at any step. Therefore, one of the biggest problems you might face is making sure that errors are minimized as much as possible. Consider what happens if you are off on your determination of the volume of air collected, the laboratory is off in determining the quantity of the chemical that was collected, someone makes a mistake on any calculations, or the worker being sampled muddles the sample during the sampling period. Each of these errors would be cumulative, so if each step introduced only a 5% error, the overall error of the exposure concentrations could be greater than 25%. The textbook has a good discussion of errors on pages 120–121 (Fuller, 2015). Therefore, how do you minimize the error when you evaluate exposures? Minimizing Errors in Sampling The first step is making sure you use validated methods for sampling and the laboratory uses validated methods for analyzing your samples. There are two organizations that publish validated and semi-validated sampling and analytical methods, the Occupational Safety and Health Administration (OSHA), and the National Institute for Occupational Safety and Health (NIOSH). Understanding how the methods are validated can help you understand how errors can enter into the evaluation process. OSHA has established a procedure for validating sampling and analytical methods. In order to be validated, research must consider five variables associated with the actual sampling, four variables associated with the laboratory analysis of the samples, and four variables associated with the overall method (Eide, Simmons, & Hendricks, 2010). The variables associated with the actual sampling are sampler capacity, sampler rate, sampling interferences, extraction efficiency, and the effects of storage (Eide, Simmons, & Hendricks, 2010). Research is conducted to determine how much of the chemical can be collected on a sampler before 5% of the chemical breaks through without being collected. The research then identifies a sampling rate or range of sampling rates for which the collection is the most efficient. Any other chemicals that could interfere with the collection of the chemical of interest by lowering the collection efficiency must also be identified. Once the chemical is collected on the sampler, it has to be extracted in order to be analyzed. The amount that can be extracted is determined and reported as a percentage. OSHA typically likes to see a collection efficiency greater than 90% (Eide, Simmons, & Hendricks, 2010). Finally, research must be performed to see how long the sampling device can be stored at specific temperatures before the chemical that was collected starts to degrade.

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The variables associated with the analytical procedure are the analytical detection limit, calibration of the analytical instrument, analytical interferences, and qualitative analysis. Basically, research must determine what is the lowest quantity of the chemical that can be detected by the analytical method, the standard error of the analysis (calibration), any chemicals that might interfere with detection of the chemical of interest during the analytical process, and means that can be used to aid in determining the chemical is present during the analysis (Eide, Simmons, & Hendricks, 2010). Overall Sampling Method Accuracy The variables associated with the overall procedure are the overall detection limit, the reliable quantitation limit, precision, and reproducibility (Eide, Simmons, & Hendricks, 2010). Basically, this analysis is used to determine, overall, what is the lowest quantity of the chemical that can be detected and quantified, how precise the results should be, and how easily the analysis can be reproduced. The detection limit and the quantitation limit are similar. The difference is that the detection limit is the lowest quantity that can be detected (i.e., the analysis shows it is there, but may not be able to determine the exact concentration), while the reliable quantification limit (RQL) is the lowest quantity of the chemical that can be reliably quantified (i.e., we can determine the exact concentration). For overall precision, OSHA requires the 95% confidence interval to be within +25% (Eide, Simmons, & Hendricks, 2010). You can see that a tremendous amount of effort must be taken to validate a sampling and analytical method used by an industrial hygienist to evaluate chemical exposures. The result is a method that will hopefully, determine exposures within + 25% of the actual exposures that are present. Of course, this means the results will likely not be 100% accurate. This will present difficulties in using the results to compare with occupational exposure limits (OEL). We will discuss these difficulties in the following unit. Choosing a Sampling Method For this lesson we will look at the procedures you would use to decide which method you would use to evaluate an exposure and then how to use the method in actual practice. For our example, we will look at NIOSH method 2027 to evaluate exposures to acetone. You can access the method using this document. Notice that the method is titled Ketones and can be used to sample for seven different ketones including acetone. The first decision the industrial hygienist must make is what sampling media to use. For ketones, method 2027 indicates that a solid sorbent tube containing two sections of silica gel (one with 500 mg and one with 1000 mg) is used (Ashley & O’Connor, 2017). It is common for a sampling tube to contain two or more sections of an adsorbent. Acetone would be collected on the first section. When acetone is detected on the second (backup) section, it indicates that breakthrough has occurred. In other words, because either the concentration of acetone was too high or the flow rate was too high, not all the acetone was collected, and some broke through the first section. Having more than 5% breakthrough on the tube can invalidate the sample results. The chosen sampling method will include a recommended flow rate or range of flow rates. Method 2027 recommends a flow rate between 0.05 liters per minute (l/min) and 0.1 l/min (Ashley & O’Connor, 2017). The recommended flow rate is based on a range of concentrations that were tested during the validation of the method. In Table 3 of the method, you can see that the range for acetone was 0.02–26 milligrams (mg) collected on the tube (Ashley & O’Connor, 2017). With experience, an IH can choose to use higher or lower flow rates depending on the expected air concentrations of acetone in the work environment. You might choose to use 0.05 l/min if you expect relatively high concentrations of acetone to be present and to use 0.1 l/min if you expect a fairly low concentration to be present. After you choose the flow rate, you must calibrate the sampling train (sample pump connected to the sampling tube) to ensure you are using the correct flow rate. There are two basic levels of calibration devices you can use: primary calibration devices and secondary calibration devices. A good discussion of the differences in the two types of calibration devices is present on page 146 of the textbook (Fuller, 2015). In some cases, industrial hygienists will calibrate a secondary calibration device like a rotameter against a primary calibration device and use the rotameter to check flow rates periodically in the field during the sampling event.

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Collecting an IH Sample Another important consideration is how long to collect a sample. The method will provide you with some guidance. For example, method 2027 recommends collecting a minimum of 2 liters of air and a maximum of 10 liters of air (Ashley & O’Connor, 2017). You can use that recommendation to calculate a minimum and maximum time to collect the samples by using the flow rate you chose. For example, if you chose to use a flow rate of 0.1 l/min and the maximum recommended air volume of 10 L, you would divide the 10 L by 0.1 l/min to get 100 minutes. Understand that the recommended volumes in the method are based on the research with the concentration shown in Table 3 of the method. If you wanted to evaluate the exposures for an employee over an entire eight-hour work shift, you could sample for a longer period if you expected exposure concentrations to be much lower than the concentrations shown in the method. The risk you take in sampling for a longer period is that you could have a breakthrough greater than 5% resulting in an invalid sample. Another approach would be to change out the sampling tube periodically, breaking up a work shift into a series of samples with lower volumes. This approach would result in additional costs for analysis. It is also important to make sure that you collect an adequate volume of air, so the analytical process can actually quantify a result that is less than the published OEL that you decide to use. For example, if you had a permissible exposure limit (PEL) of 0.1 parts per million (ppm) for a chemical, but you did not collect an adequate volume of air, your reported analytical result could be <0.2 ppm. This result would be inadequate for your evaluation because the exposure could be above the PEL, but you would not know that. Therefore, it can be important to be able to calculate the minimum volume of air required to receive results that are less than the OEL you choose. This is one of the calculations you will be required to complete for this unit’s assignment. Basically, you use the limit of quantification for the chemical that is reported in the method and the flow rate you choose from the method. There is a PowerPoint presentation that you can access in the required readings section that guides you through the calculations required. The textbook also contains a discussion of the calculation on page 122 (Fuller, 2015). Personal Versus Area Samples A final consideration is whether you will collect personal samples or area samples. Personal samples are placed on the worker with the collection media placed within the worker’s breathing zone. OSHA (2014) has defined the breathing zone as being as close to the worker’s nose and mouth as possible in a hemisphere forward of the shoulders six inches to nine inches from the nose and mouth. An area sample is simply a sample that is placed within an area to determine the concentration in the area. For sampling to evaluate the risks associated with personal exposures, personal samples are the preferred method. After you complete the sampling, you calibrate the flow rate of the sampling train again to determine if there was any change in flow rate. There is no set difference that is required, but most industrial hygienists will invalidate a sample if the difference between the two calibrations is greater than 10%. You must then review the method one more time to see if there are any special requirements for shipping. Some samples must be shipped in a cooler with an ice pack to maintain a low temperature. Other samples must be placed in a stabilizing solution prior to shipping. The chosen method will tell you if anything is required. Method 2027 shows that there are no special requirements for shipping the acetone samples (Ashley & O’Connor, 2017). There are other types of sampling that do not use sampling media and sampling pumps. For example, noise exposures are evaluated using either a sound level meter (SLM) or, more commonly, a noise dosimeter. The SLM and dosimeter also have to be calibrated prior to use. Manufacturers have a calibration method for their devices. Pages 248 and 249 of the textbook contain information about evaluating noise exposures (Fuller, 2015).

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References Ashley, K., & O’Connor, P. F. (Eds.). (2017). NIOSH manual of analytical methods (NMAM) (5th ed.).

Retrieved from https://www.cdc.gov/niosh/nmam/default.html Eide, M., Simmons, M., & Hendricks, W. (2010). Validation guidelines for air sampling methods utilizing

chromatographic analysis (Publication Index No. T-005). Retrieved from https://www.osha.gov/dts/sltc/methods/chromguide/chromguide.pdf

Fuller, T. P. (2015). Essentials of industrial hygiene. Itasca, IL: National Safety Council. Occupational Safety and Health Administration. (2014). OSHA technical manual: Section II, Chapter 1,

Personal sampling for air contaminants. Retrieved from https://www.osha.gov/dts/osta/otm/otm_ii/otm_ii_1.html

Suggested Reading You are encouraged to look at some of the methods in each publication as you will using these during some of the assignments for the course. The OSHA methods can be accessed at the Alphabetic Index of Sampling and Analytical Methods web page. The NIOSH methods are published as the NIOSH Manual of Analytical Methods (NMAM) 5th Edition. In order to access the following resources, click the links below. The CSU Online Library contains many articles that relate to the Unit III readings. The following are just a few of the related articles that can be found in the Academic Search Complete database. Industrial hygienists can use two basic methods to evaluate personal exposures to chemicals, active or passive sampling. Active sampling uses a sampling pump with some type of collection media. Passive sampling uses a sampling badge with no sampling pump. The following article evaluates the results from sampling using both methods for formaldehyde. Lee, E. G., Magrm, R., Kusti, M., Kashon, M. L., Guffey, S., Costas, M. M., Harper, M. (2017). Comparison

between active (pumped) and passive (diffusive) sampling methods for formaldehyde in pathology and histology laboratories. Journal of Occupational and Environmental Hygiene, 14(1), 31–39. Retrieved from https://libraryresources.columbiasouthern.edu/login?url=http://search.ebscohost.com/login.aspx?direc t=true&db=a9h&AN=120263473&site=ehost-live&scope=site

Advances in consumer electronics have produced numerous apps that can be used by anyone with a smart phone. One app allows you to monitor noise levels as if your phone were a sound level meter. The question is, how accurate are the readings? The following article reports the results of a comparison of readings using a calibrated sound level meter and three different apps. Ibekwe, T. S., Folorunsho, D. O., Dahilo, E. A., Gbujie, I. O., Nwegbu, M. M., & Nwaorgu, O. G. (2016).

Evaluation of mobile smartphones app as a screening tool for environmental noise monitoring. Journal of Occupational and Environmental Hygiene, 13(2), D31–D36. Retrieved from https://libraryresources.columbiasouthern.edu/login?url=http://search.ebscohost.com/login.aspx?direc t=true&db=a9h&AN=112262955&site=ehost-live&scope=site

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New sampling methods are periodically developed. We discussed some of the validation variables that must be determined. The following article summarizes the methods used to determine the optimal flow rate for a new device used for performing size-selective samples. These types of samples are used when the chemical hazard of concern is only the respirable fraction of particulates that are present. Lee, T., Thorpe, A., Cauda, E., Tipton, L., Sanderson, W. T., & Echt, A. (2018). Laboratory comparison of new

high flow rate respirable size-selective sampler. Journal of Occupational and Environmental Hygiene, 15(10), 755–765. Retrieved from https://libraryresources.columbiasouthern.edu/login?url=http://search.ebscohost.com/login.aspx?direc t=true&db=a9h&AN=133105290&site=ehost-live&scope=site

An alternate approach to evaluating exposures in the workplace is to use real-time, direct-reading instruments. These types of instruments are limited in their ability to take time-weighted average samples in the worker’s breathing zone. The following article evaluates a new portable instrument that is said to be more suitable for collecting samples from a worker’s breathing zone. Soo, J.-C., Lee, E. G., LeBouf, R. F, Kashon, M. L., Chisholm, W., & Harper, M. (2018). Evaluation of a

portable gas chromatograph with photoionization detector under variations of VOC concentration, temperature, and relative humidity. Journal of Occupational and Environmental Hygiene, 15(4), 351– 360. Retrieved from https://libraryresources.columbiasouthern.edu/login?url=http://search.ebscohost.com/login.aspx?direc t=true&db=a9h&AN=128834249&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. The National Institute for Occupational Safety and Health (NIOSH) publishes validated sampling and analytical methods for chemical hazards that are used by most industrial hygienists. Access the document NIOSH Manual of Analytical Methods (NMAM) at https://www.cdc.gov/niosh/nmam/default.html. Look for analytical methods for some chemicals you are familiar with. Are there some chemicals you use that do not have a validated method in NMAM?