Solved by verified expert:Unit V Homework AssignmentWelding fumes are a common occupational exposure. Several different welding fumes can cause similar adverse health effects. Personal sampling of a welding operation at a manufacturing facility produced the following 8-hour time-weighted average (TWA) results for individual metal fumes.Metal FumeAntimony Beryllium Cadmium Chromium CopperIron Oxide Magnesium Oxide Molybdenum NickelZinc Oxide(R) Respirable fraction (I) Inhalable fractionResult0.05 mg/m3 0.00001 mg/m3 0.025 mg/m3 0.02 mg/m3 0.03 mg/m3 0.5 mg/m3 0.02 mg/m3 0.003 mg/m3 0.25 mg/m3 0.3 mg/m3OSHA PEL0.5 mg/m3 0.002 mg/m3 0.1 mg/m3 1 mg/m3 0.1 mg/m3 10 mg/m3 15 mg/m3 15 mg/m3 1 mg/m35 mg/m3ACGIH TLV0.5 mg/m3 0.00005 mg/m3 (I) 0.01 mg/m3 0.5 mg/m3 0.2 mg/m35 mg/m3 (R) 10 mg/m310 mg/m3 (I) 1.5 mg/m3 (I)2 mg/m3 (R)Briefly summarize the primary health effects associated with overexposure to each type of metal fume, including both acute and chronic health effects. Explain what analytical methods you would use for evaluating health hazards in the workplace.Identify the types of metal fumes that would produce similar health effects on an exposed worker. Calculate the equivalent exposure (in relation to OSHA PELS) for the metal fumes with similar health effects based on the “Result” column in the table above. Discuss whether you believe any of the individual metal fume exposures or the combined exposure exceeds an OSHA PEL or an ACGIH TLV.Your homework assignment should be a minimum of two pages in length.
unitv_industrial_hygiene_study_guide.pdf
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UNIT V STUDY GUIDE
Evaluating Exposures to Particulates
Course Learning Outcomes for Unit V
Upon completion of this unit, students should be able to:
2. Apply scientific principles to the practice of industrial hygiene.
2.1 Explain the analytical methods to be used for evaluating health hazards in the workplace.
6. Perform basic calculations related to industrial hygiene.
6.1 Calculate the equivalent exposure given a group of exposure results and the applicable OSHA
PELs.
Course/Unit
Learning Outcomes
2.1
6.1
Learning Activity
Unit V Lesson
Article: “Sampling efficiency of modified 37-mm sampling cassettes using
computational fluid dynamics”
Unit V Homework Assignment
Unit V Lesson
Article: “Generation and behavior of airborne particles (aerosols)”
Unit V Homework Assignment
Reading Assignment
To access the following resources, click the links below:
Anthony, T. R., Sleeth, D., & Volckens, J. (2016). Sampling efficiency of modified 37-mm sampling cassettes
using computational fluid dynamics. Journal of Occupational and Environmental Hygiene, 13(2), 148158. Retrieved from
https://libraryresources.waldorf.edu/login?auth=CAS&url=http://search.ebscohost.com.libraryresource
s.waldorf.edu/login.aspx?direct=true&db=a9h&AN=112262952&site=ehost-live&scope=site
Baron, P. (n.d.). Generation and behavior of airborne particles (aerosols) [PowerPoint slides]. Retrieved from
https://www.cdc.gov/niosh/topics/aerosols/pdfs/Aerosol_101.pdf
Brown, J. S., Gordon, T., Price, O., & Asgharian, B. (2013). Thoracic and respirable particle definitions for
human health risk assessment. Particle and Fibre Toxicology, 10(12), 1-12. Retrieved from
http://particleandfibretoxicology.biomedcentral.com/articles/10.1186/1743-8977-10-12
Unit Lesson
We discussed gases and vapors in Unit IV. Aerosols are another group of fairly common health hazards in the
occupational environment. The terms particles, particulates, and aerosols are often used interchangeably.
The National Institute for Occupational Safety and Health (NIOSH) defines aerosols as the suspension of tiny
particles or droplets in the air. The most common types of aerosols in the workplace are dusts, fumes, and
mists.
Identifying types of aerosols in the workplace may be difficult because aerosols can be generated by the work
process and may not be listed on any safety data sheet (SDS). Additionally, the action producing the aerosols
may generate different sizes of aerosols. The size of the airborne particles can influence where harm may
occur in workers exposed to the aerosol.
OSH 4301, Industrial Hygiene
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The human respiratory system can be divided into three main areas. The upper
region
is the head
area. The
UNIT
x STUDY
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middle area is the tracheobronchial region. The lower area is the gas exchange
or alveolar region. (Brown,
Title
Gordon, Price, & Asgharian, 2013). The size of particles in the air can be very important in determining where
the particles will penetrate and lodge.
This is important if the damage that can
be caused by those particles is limited to
one of the three areas of the respiratory
system. For example, if an aerosol is
associated with cancer in the gas
exchange region of the respiratory
system, the airborne particles would have
to be small enough to penetrate to the
alveolar region. This concept has been
used in establishing some occupational
exposure limits (OELs). The
Occupational Safety and Health
Administration (OSHA) has established
some permissible exposure limits (PELs)
A picture of an aerosol can being sprayed. Image by Howie is licensed
for aerosols as total particulates and
under CC BY 2.0
some PELs as respirable particulates
(Howie, 2012)
(NIOSH, 1994; NIOSH, 1998).
The mean size of the particle that can enter the different regions has been widely studied. Some common
terms associated with the particle sizes required to penetrate the different regions are total fraction, inhalable
fraction, thoracic fraction, and respirable fraction. The total fraction is the total amount of particulates in the
air, without regard to size. The inhalable fraction is defined as particles that can be inhaled through the mouth
and nose. The thoracic fraction is defined as particles that can penetrate past the larynx to the middle region
of the respiratory system. The respirable fraction is defined as particles than can penetrate to the alveolar
region of the respiratory system (Brown, Gordon, Price, & Asgharian, 2013). However, the lung is not 100%
efficient at capturing the particles in each region. Historically, inhalable particles have been defined as <100
µm mean diameter, thoracic particles as <10 µm mean diameter, and respirable particles as <4 µm mean
diameter.
To date, OSHA has only established PELs for aerosols that fit into either the total or respirable fraction of
aerosols in the air. The majority of validated sampling methods for aerosols use some type of filter, either
treated or untreated. One of the most frequently used particulate sampling methods is NIOSH method 0500,
“Particulates Not Otherwise Regulated, Total” (NIOSH, 1994). This method utilizes an untreated polyvinyl
chloride (PVC) filter that is weighed prior to sampling and weighed again after sampling to determine the total
amount of particulate collected on the filter. This method collects all particles deposited onto the filter, so it is
not able to distinguish those particles in the air with the ability to penetrate to lower areas of the respiratory
system and cause harm.
A similar sampling method, NIOSH method 0600, “Particles Not Otherwise Regulated, Respirable” also uses
an untreated pre-weighed PVC filter but places a particle separation device, like a cyclone, in the sampling
train to separate out respirable and non-respirable particulate (NIOSH, 1998). The particle separation devices
will have a published operating parameter describing the size of the particles that will be filtered out. A term
that is commonly used is the cut size. This is also referred to as 50% sampling efficiency or the cut point. The
term refers to the median size where the sampler is efficient at capturing 50% of particles at that flow rate.
The cut size will vary depending on the sampler used and the flow rate. The published median diameter
(OSHA and NIOSH) for respirable samples has been 4 µm. For example, SKC manufactures the SKC
Aluminum Cyclone widely used by industrial hygienist. SKC has published their sampling efficiency curves,
and at a flow rate of 2.5 liters per minute (LPM), the 50% cut point is 4 µm. Using a flow rate of 2.8 LPM
changes the 50% cut point to 3.5 µm. Therefore, most industrial hygienist will use the 2.5 LPM flow rate
sampling with the SKC cyclone. Another commonly used cyclone is the Zefon Nylon Dorr-Oliver Cyclone. It
has a 50% cut point of 4 µm at a flow rate of 1.7 LPM, so most industrial hygienist will use that flow rate if they
use the Dorr-Oliver cyclone (NIOSH, 1998).
The American Conference of Governmental Industrial Hygienists (ACGIH) and many countries in Europe
have implemented standards that utilize inhalable, thoracic, and respirable fractions instead of total and
respirable fractions. The respirable fractions are the same as the respirable fractions used by OSHA, and the
OSH 4301, Industrial Hygiene
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same samplers are used. The OELs based on inhalable and thoracic fractionsUNIT
are thought
to be
more
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representative of actual deposition in the human respiratory system, so they would
Title provide greater protection
for workers.
Sampling for inhalable and thoracic fractions of airborne aerosols requires different types of particle
separation devices. The most common samplers for inhalable fractions are the IOM Inhalable Sampler and
the Button Sampler, both made by SKC. The IOM sampler has a 50% cut point of 100 µm at a 2.0 LPM flow
rate. The button sampler has a 50% cut point of 100 µm at a 4.0 LPM flow rate that increases sensitivity. SKC
also manufactures a series of thoracic samplers with a 50% cut point of 10 µm for flow rates ranging from 2
LPM to 8 LPM. (OSHA, 1970b).
One term that is often misused is fume. Media and some safety and health professionals often use the terms
fumes, vapors, and gases interchangeably; however, fumes are, in fact, aerosols, not gases or vapors. A
fume is generated when a solid is heated to a temperature that generates a vapor. Once airborne, the
temperature does not remain elevated enough to maintain the vapor, and the compound becomes particles in
the air. Those particles are called fumes. The individual particles will sometimes agglomerate, forming larger
particles. For a summary of how agglomeration occurs, see the second required reading for this unit.
Understanding the differences between fumes, gases, and vapors can be important for air sampling as well
as choosing and implementing control methods.
The NIOSH sampling and analytical methods mentioned earlier are commonly used for sampling aerosols
covered by the particles not otherwise regulated (PNOR) PEL. In some instances, the specific aerosols
present in the air are important in evaluating personal exposures. For these aerosols, OSHA, NIOSH, and
ACGIH have established an OEL. For example, many of the individual metal fumes generated during welding
operations have individual PELs, RELs, and TLVs. OSHA’s Table Z-1 notes several PELs for metal fumes,
including copper, iron oxide, magnesium oxide, and zinc oxide fume (OSHA, 1970b). Some PELs for metal
fumes are published in OSHA’s Table Z-2, including one for beryllium fume. Still other metal fumes have
substance-specific standards published. See 29 CFR 1910.1025 for the lead standard, which applies to
exposure to lead fume, and 29 CFR 1910.1027, which applies to cadmium fume exposure (OSHA, 1970c;
OSHA, 1970d). For OSHA standards, the PELs are all based on the total fraction of the airborne fume.
To conduct sampling for the specific metal fumes, more laboratory analysis will be required than simply preweighing and post-weighing a filter. Samples for metal fumes are commonly collected on a mixed cellulose
ester (MCE) filter instead of a PVC filter, using either NIOSH Method 7300 or OSHA Method ID 121. These
methods require the filter to be digested at the lab and then analyzed using either inductively coupled plasma
spectrometry or atomic absorption methods.
Another method for monitoring particulate levels uses real-time meters. While these meters can separate
particles into different size ranges, they do not identify specific particles. In other words, there is no crystalline
quartz meter that can tell you the exact concentration of crystalline quartz in the air. However, particle meters
can be useful for screening areas to determine where personal sampling should be performed or for
monitoring particle levels in controlled areas to evaluate the effectiveness of controls.
Sometimes, different aerosols produce similar health effects in humans. When these aerosols are present in
the same area, the evaluation should consider the exposures to both the individual compounds and the
combination of all compounds. OSHA calls this the equivalent exposure (OSHA, 1970a).
The formula for calculating the equivalent exposure is in 29 CFR 1910.1000(d)(2)(i). It is necessary to
understand the formula to complete the assignment for this unit.
References
Brown, J. S., Gordon, T., Price, O., & Asgharian, B. (2013). Thoracic and respirable particle definitions for
human health risk assessment. Particle and Fibre Toxicology, 10(12), 1-12. Retrieved from
http://particleandfibretoxicology.biomedcentral.com/articles/10.1186/1743-8977-10-12
OSH 4301, Industrial Hygiene
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Howie, R. (2012, April 1). Spray: Aerosol backlit with flash [Photograph]. Retrieved
UNIT from
x STUDY GUIDE
https://www.flickr.com/photos/rmhowie/6889038174/in/photolist-buL83f-8LtqME-8dNwbe-7TSYQ8Title
roFMNf-6GZPfP-3a8TT6-a6AGab-og6ogF-qE9jjV-8Ap7nL-aBSmzx-bHESxv-2jJPmD-nDp8s2b6x4fp-2o8NZZ-qE7cJG-6M26ND-2o8P6D-aachWW-6FgpVg-6CKEAv-6M2qEP-arnzm5-arnzFW5TUqiP-2miS
National Institute for Occupational Safety and Health. (1994). Particulates not otherwise regulated, total:
Method 0500. In P. M. Eiler & M. E. Cassinelli (Eds.), NIOSH manual of analytical methods (4th ed.).
Retrieved from http://www.cdc.gov/niosh/docs/2003-154/pdfs/0500.pdf
National Institute for Occupational Safety and Health. (1998). Particulates not otherwise regulated,
respirable: Method 0600. In P. M. Eiler & M. E. Cassinelli (Eds.), NIOSH manual of analytical
methods (4th ed.). Retrieved from http://www.cdc.gov/niosh/docs/2003-154/pdfs/0600.pdf
Occupational Safety and Health Administration. (1970a). Occupational safety and health standards: Toxic and
hazardous substances (Standard No. 1910.1000). Retrieved from
https://www.osha.gov/pls/oshaweb/owadisp.show_document?p_id=9991&p_table=STANDARDS
Occupational Safety and Health Administration. (1970b). Occupational safety and health standards: Toxic and
hazardous substances (Standard No. 1910.1000 Table Z-1). Retrieved from
https://www.osha.gov/pls/oshaweb/owadisp.show_document?p_table=standards&p_id=9992
Occupational Safety and Health Administration. (1970c). Occupational safety and health standards: Toxic and
hazardous substances (Standard No. 1910.1025). Retrieved from
https://www.osha.gov/pls/oshaweb/owadisp.show_document?p_table=STANDARDS&p_id=10030
Occupational Safety and Health Administration. (1970d). Occupational safety and health standards: Toxic and
hazardous substances (Standard No. 1910.1027). Retrieved from
https://www.osha.gov/pls/oshaweb/owadisp.show_document?p_table=STANDARDS&p_id=10035
Suggested Reading
To access the following resource, click the link below:
Traditional industrial hygiene sampling for particulates uses a calibrated personal sampling pump and a filter.
This method may not be ideal when instantaneous measurements are desired at a workplace. There are
some real-time particulate meters available to the industrial hygienist, but their accuracy has been
questioned. The article below compares some of the more commonly used particulate meters to an accepted
NIOSH method used for diesel particulate.
Yu, C. H., Patton, A. P., Zhang, A., Fan, Z.-H., Weisel, C. P., & Lioy, P. J. (2015). Evaluation of diesel exhaust
continuous monitors in controlled environmental conditions. Journal of Occupational and
Environmental Hygiene, 12(9), 577–587. Retrieved from
https://libraryresources.waldorf.edu/login?auth=CAS&url=http://search.ebscohost.com.libraryresource
s.waldorf.edu/login.aspx?direct=true&db=a9h&AN=109017154&site=ehost-live&scope=site
Learning Activities (Nongraded)
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.
An animated computer program designed to help introductory students learn about aerosols was created
using a National Science Foundation’s grant. The program is accessible at
http://aerosol.ees.ufl.edu/index.html
Complete the nine modules to increase your knowledge of aerosols.
OSH 4301, Industrial Hygiene
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