UNIT V, VI & VIII

MOS 6301, Advanced Industrial Hygiene 1 Cou rse Learning Outcomes for Unit V Upon completion of this unit, students should be able to: 7. Evaluate common industrial hygiene related hazard assessment and control strategies. 7.1 Explain common industrial hygiene sampling procedures that evaluate chemical hazards. 7.2 Discuss how different methods used to perform a risk assessment for chemical and biological hazards can affect the accuracy and precision of the data. Reading Assignment Chapter 6 : Gases and Vapors, pp. 119 –135 Chapter 7 : Aerosols, pp. 144 –157 Chapter 10 : Dermal Hazards, pp. 225 –233 Chapter 15 : Biological Hazards, pp. 361 –369 Unit Lesson Anticipation and recognition of chemical and biological hazards are the first steps in controlling exposures and reducing risk. However, each hazard should be evaluated in order to assess the risk associated with the hazard. The risk assessment allows the industrial hygienist to prioritize chemical and biological hazards when recommending workplace controls. Evaluation is also the primary method used to determine compliance with occup ational exposure limits (OELs). Evaluation of chemical hazards is typical ly performed using some type of air monitoring. Surface sampling is also sometimes used, but most OELs are based on inhalation exposure. OSHA allows employers to use modeling to estimate exposures instead of air sampling, but this method can be complex and is not widely used in practice. An important decision that an industrial hygienist must make is how to evaluate chemical exposures.

Decisions must be made on whether to use grab sampling methods or continuous monitoring methods. Grab samples will only p rovide an estimate of an exposure for a limited time period, while continuous monitoring provides a time -weighted average concentration for the hazard. The toxicity of the hazard will influence the decision on the type of sample that is collected. Chemical s with high acute toxicity will generally have either a short -term exposure limit (STEL) or a ceiling limit established, and grab sampling may be the best approach for the evaluation. Other chemicals that have limited acute toxicity or that also have chron ic health effects will have time -weighted average (TWA) OELs established, and continuous sampling is more effective for an evaluation. With either method of sampling, the industrial hygienist has a wide range of sampling methods available. Some direct read meters and sampling tubes are available for both grab sampling and continuous sampling.

Colorimetric tubes used for sampling have been used for decades. However, the tubes do not typically have the accuracy and precision required for the e valuation of chemical hazards. Therefore, they are typically used as a screening tool by industrial hygienists. Some long duration colorimetric tubes are an exception and are commonly used for evaluation, especially when other methods are limited. Colorime tric tubes for UNIT V STUDY GUIDE Evaluation of Chemical and Biological Hazards Commonly Present in Industrial Settings MOS 6301, Advanced Industrial Hygiene 2 UNIT x STUDY GUIDE Title carbon monoxide exposure are commonly used because there is no validated method for sampling with laboratory methods. There are many direct read meters available that can detect the presence of chemical hazards. These meters are usually acc urate enough to use while evaluating a hazard. However, there are a limited number of chemical hazards for which meter sensors exist. There are some meters that will only provide a grab sample result, and there are some meters that also have data -logging c apabilities and can provide a continuous sample result. Some of the meters are designed as personal meters to be worn by workers in order to provide individual results. With a limited number of sensors available, the use of these personal meters is also li mited. There are some larger meters that can analyze many additional chemical hazards. The size of the meters limits their use for personal sampling, but larger meters can be used for area samples. Personal and area sampling with laboratory analysis has been used by industrial hygienists for the evaluation of chemical hazards. Air sampling data are only as accurate and precise as the sampling and analytical methods that are used to produce them. If accuracy and precision are not reliable, the results will not produce a good risk assessment. Errors in accuracy and precision typically are introduced into the data either during the sample collection (sampling error) or during laboratory analysis (laboratory error). In general , the Occupational Safety and Heal th Administration (OSHA ) requires the overall error to be less than 15%. In order to evaluate error, sampling/analytical methods undergo a process called validation . An analytical method is evaluated for error at both the sample collection and laboratory a nalytical stage to estimate t otal sampling error. Industrial hygienists should only use validated sampling/analytical methods for the evaluation of chemical and biological hazards. There are two major organization s that publish validated methods: OSHA and the National Institute for Occupational Safety and Health (NIOSH). The OSHA methods are published under the title “Sampling and Analytical Methods” and can be accessed at www.osha.gov/dts/sltc /methods/index.html . The NIOSH methods are published in a document titled “NIOSH Manual of Analytical Methods (NMAM) ” and can be accessed at http://www.cdc.gov/niosh/docs/2003 - 154/default. html . The chemical state of the hazard can affect how an air sample is collected. In general, there are two basic types of air sample methods that are commonly used by industrial hygienists . Some methods use a badge to collect the sample, and some methods use a sampling pump with some type of media in line. Sampling with pumps and media has been a mainstay in the field for many years . The use of sampling badges is a more recent development. Each year, manufacturers validate collection and analytical methods for additional chemicals, expanding the number of badges available to the industrial hygienist. One source of error in the sampling process is calculating the volume of air that chemicals come from . For badges, flow rates are calculated by the ma nufacturer, and the industrial hygienist must record the number of minutes that the badge was open. For sampling pumps, the industrial hygienist must calibrate the flow rate of the sampling pump and also record the time air was being drawn through the samp ling media. Mistakes in calibration and in recording sampling times will introduce sampling errors into the data. Calibration of sampling pumps is a very important task that an industrial hygienist performs during an evaluation. Calibration is performed u sing some type of calibration device . There are two basic levels of calibration devices that the industrial hygienist uses: primary calibration devices and secondary calibration devices . Understanding the differences between the two calibration devices can prevent unnecessary sampling errors. Primary calibration devices use a method where a known volume of air is pulled through the device. The original primary calibration device that most industrial hygienists used in the past was a frictionless flow meter, often called a soap bubble flow meter . These devices are still in use today, but the devices require the use of a soap solution, a stop watch, and some calculations. In the late 1980s and in the following years, manufacturers have introduced primary calib ration devices that provide the flow rate as a direct read. The two most commonly used primary calibrators are the Gilian Gilibrator, which uses a soap solution inside the device, and the BIOS DryCal, which uses a frictionless piston with no liquid solutio n. Secondary calibration devices are not as accurate as primary calibration devices and must be calibrated against a primary calibration device prior to use. This is an example of where error may enter the sampling process. If a secondary calibration dev ice is used without calibration against a primary calibration device, errors in flow rates are probable. The most common secondary calibration devices that industrial hygienists use are rotameters. You can purchase rotameters with a variety of scales and r eliability. Precision rotameters are also available, but they still must be calibrated against a primary standard. MOS 6301, Advanced Industrial Hygiene 3 UNIT x STUDY GUIDE Title Another aspect of air sampling is choosing the correct sampling media. Using incorrect sampling media can invalidate the sampling data or, i n some cases, make the samples impossible to analyze. A wide variety of sampling media exists for a wide variety of chemical hazards. It would be extremely difficult for the industrial hygienist to memorize all of the sampling media available and the diffe rent chemical hazards for which they can be used. Each of the sampling methods will also require specific sampling rates to be used. The validated methods published by OSHA and NIOSH include a sampling section that lists the correct sampling media and reco mmended flow rates. In addition, most analytical laboratories will include charts that show the sampling media of choice and recommended flow rates. These resources make the industrial hygienist’s job much easier. Finally , the industrial hygienist will so metimes encounter chemical hazards for which a validated method does not exist . Evaluating exposures to these chemical hazards is much more difficult. Establishing a relationship with a reliable analytical laboratory can make the task easier. Some laborato ries will work with an industrial hygienist to either develop a validated sampling/analytical method (which can be very expensive) or modify an existing validated method for the chemical hazard to be evaluated. Suggested Reading The CSU Online Library c ontains many articles that relate to the reading assignment within this unit. In order to access the resource s below, you must first log into the myCSU Student Portal and access the Academic Search Complete database within the CSU Online Library. Some evaluation of chemical levels must be performed using direct read meters because there are no validated sampling/analytical methods . The following article looks at the use of direct read meters to monitor oxygen levels in a work environment . McManus, N., & Haddad, A. N. (2015). Oxygen levels during w elding. Professional Safety , 60 (7), 26 -32. Biological hazards are typically more difficult to evaluate. The following article describes one sampling method for biological hazards. O’Brien, K. M., & Nonn enma nn, M. W. (2016). Airborne influenza A Is detected in the personal breathing zone of swine v eterinarians. Plos ONE , 11 (2), 1 -8. Some threshold limit values (TLVs) use inhalable fractions of dust instead of the total dust fraction used by the Occupational Safety and Health Administration (OSHA) . Evaluating exposures using the TLVs requires the use of different sampling devices. The authors of the article below reported the results of using inhalable samplers and polyurethane foam (PUF) media to estimate exp osures to particles that could be deposited in the upper respiratory system. Especially note the photographs in Figure 5 of the inhalable samplers that were used. Click here to access the resource below. Sleeth, D. K., Balthaser, S. A., Collingwood, S., & Larson, R. R. (2016). Estimation of the human extrathoracic deposition fraction of inhaled particles using a polyurethane foam collection substrate in an IOM sampler. International Journal of Envi ronmental Research and Public Health , 13 (3), 292. Retrieved from http://www.mdpi.com/1660 -4601/13/3/292/htm Learning Activities (Non -Graded) Non -graded 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 the NIOSH Manual of Analytical Methods (NMAM) which can be accessed at http://www.cdc.gov/niosh/docs/2003 -154/default.html . Access the NMAM , and read the sampling/analytical methods for several chemicals with which you are familiar. See if you can determine which sampling media you should use, the flow rate(s) that are recommended, and the sampling times that are suggested . How do the sampling methods and analytical methods differ for vapors and gases and aerosols?