CHAPTER
12 SOLUTIONS TO END-OF-CHAPTER EXERCISES
12.1. The
employer of the employees who will be potentially exposed.
12.2. Selection
of appropriate PPE equipment, fit testing, and PPE training for affected
employees. The training must be documented with a certificate that identifies
the names of employees trained, the dates, and the subject for which the
employee was certified.
12.3. Retraining
is needed if either the workplace is changed or if the PPE is changed.
12.4. Simply
attaching a lifeline to a worker’s belt may not be adequate. The belt may not
withstand the shock load of an accidental fall. Further, the practice might
engender a false sense of security on the part of the worker, who might think
that he/she is protected, but in truth the protection might not be adequate for
the hazard.
12.5. The
non-mandatory appendices to the OSHA standards can provide some guidance. NIOSH
publishes some data to assist employers in this decision and also publishes the
list of NIOSH certified equipment. The preambles to the OSHA standards can also
be helpful in this regard. Table 12.1 of the text provides some guidance for
eye and face protection. Expert consultants can also be beneficial, but the
hazard usually dictates the choice of equipment or at least greatly narrows the
choice.
12.6. Whenever
it is determined that the personal protective equipment is needed.
12.7. The
employee needs to learn that PPE is limited to a finite useful life even under
proper care and maintenance.
12.8. By
documentation with a certificate showing names, dates, and subject for which
the employee is certified. Employees should be knowledgeable of the subject for
which they are trained. If the workplace or the equipment changes, the employee
should be retrained.
12.9. Ordinary
cotton balls, without impregnation with a wax, are virtually worthless for
noise attenuation.
12.10. Helmets.
Helmets can also be designed to serve the function of a hardhat.
12.11. The organic substances present in
expandable foam do not have adequate warning properties, so the user will not
know when the canister is saturated.
12.12. A chemical oxygen-generating unit
employs a superoxide of potassium in which oxygen is liberated by contact with
water. Used in "closed circuit"
breathing apparatus, the moisture is supplied by the user's breath. A water flooding of the potassium superoxide
is almost sure to cause an explosion.
12.13. "Closed-circuit" respirators
would be best for circumstances when use of a self-contained breathing
apparatus is required for extended periods of time because
"closed-circuit" respirators can be smaller and lighter per minute of
maximum permissible use than "open-circuit" respirators.
12.14. Pressure demand. If the facepiece becomes leaky, the
"demand flow" type would allow the contaminant to enter the mask.
12.15. Training of employees to beware of and
test for hazardous atmospheres in tanks, and training in emergency situations
(including first aid). Management should
have procedures requiring testing of possible hazardous areas, and the wearing
of personal protective equipment for employees working in areas where hazards
do exist.
12.16. Street safety lenses and industrial
safety lenses.
Industrial
safety lenses are more durable.
12.17. Requiring workers to wear protective
equipment in areas where the protective equipment is not needed may result in
workers not respecting the rules, leading to injuries to workers.
12.18. Operators of grinding machines, drill
presses, and lathes. Also any other
machining operations that produce chips or sparks.
12.19. Federal regulations require a respirator
to be labeled as "organic vapor respirator" because it has passed a
certain prescribed test, even though the respirator may be useless for certain
organic vapors. There are so many
organic vapors that it would be impossible to label a respirator for all
organic vapors against which it is effective.
Manufacturers' recommendations (tables) should be consulted.
12.20. Hardhats are personal protective
equipment and do not "prevent accidents;" they only minimize the adverse effects of
accidents. Engineering controls to
remove the hazard is a preferable approach, but since elimination of all risk
is impractical, there is a need for personal protective equipment such as
hardhats.
12.21. The need for personal protective
equipment implies that the hazard has not been eliminated or controlled.
12.22. The employee may have inadequate
equipment, yet the employer still is responsible to provide adequate protection
to its workers. Also, employee-owned
inadequate equipment can create a dangerous, false sense of security.
12.23. The undersized manholes prevent entry of
personnel wearing self-contained breathing apparatus.
12.24. In an actual fall the shock load applied
to the fall protection system would be much greater than the static load of the
wearer’s body weight.
12.25. Use wire baskets for handling the parts
in the solvent. Substitute soap and
water for the trichloroethylene in some cases.
Change the process to eliminate the need for washing parts.
12.26. In the heat of the emergency there is a
strong tendency to try to save the first victim. There is a tendency for the rescuer to think
that what happened to the first victim will not happen to him, because he is
already aware of the danger and thinks that he can be especially alert to his
own symptoms and get out quickly if he gets into trouble.
12.27. 1. Oxygen deficiency (primary hazard)
2.
Mechanical entrapment
3. Engulfment (from granular solid
material)
4. Oxygen-rich atmosphere (fire
hazard, especially to welders)
5.
Highly toxic atmospheres
6. Escape impairment from mildly
toxic, but temporarily paralyzing
atmospheres.
12.28. Engulfment is entrapment in a fluid-like
granular solid, such as grain or sand, which causes the victim to sink deeper
with every movement. Death comes from
suffocation due to the breathing passages becoming blocked or due to the source
of air being cut off by the engulfing material.
In addition, death can come due the crushing weight of the material
closing in around the victim.
12.29. This hazard is called “entrapment.” Most mechanical entrapments occur in a space
that is ever-tightening and restricting as it descends. As the victim moves to attempt to free
him/herself he slides deeper into the more restricted space, further impairing
his freedom to move and free himself.
Eventually, the restriction firmly traps the victim, and no escape is possible
without rescue. Death can come relatively
quickly from suffocation in the small dimensions of the breathing space near
the victim. If adequate oxygen supply is
available to the victim, an even worse death can come agonizingly slowly.
12.30. Inerting is intended to reduce oxygen
content to reduce the hazards of fire, especially around welding
operations. However, oxygen deficiency
becomes a suffocation hazard to any workers in the oxygen deficient space.
12.31. Oxygen enrichment causes fires to ignite
easily and burn furiously. In situations
that most workers would expect to be harmless, oxygen-enriched atmospheres can
cause surprising ignitions.
12.32. IDLH means "immediately dangerous
to life or health" and usually refers only to the toxicity
of the particular air contaminant present.
However, in a confined space, an air contaminant that might only be a
mild depressant under normal circumstances could become lethal by paralyzing
the victim and preventing his or her escape from the danger zone.
12.33. Close all valves that govern piping that
might lead dangerous liquids, gases, or even solids into the confined
space. Use a double-block-and-bleed
procedure that closes two valves in series in a pipe leading into the space,
and in addition opens a small bleed valve in the pipe in the space between the
two major valves. The bleed valve allows
the escape of any fluids that might accumulate due to high pressure
differential on the primary major valve.
The secondary major valve thus has little or no pressure differential
across it and can achieve a positive closure.
Another procedure for positive isolation is “blanking” or “blinding,” in
which a solid plate is installed in the line completely covering the
cross-sectional area of the pipe and absolutely blocking flow. Another procedure is to physically sever the
line and detach and separate the two remaining lengths of pipe.
12.34. Oxygen deficient atmosphere. A gas mask is an air purifying device and
thus removes air contaminants but does not add the crucial ingredient ---
oxygen.
12.35. Hydrogen
fluoride and cadmium vapors are insidious in that their immediate effects are
transitory. Thus, even if these
transient effects are severe, they may pass without medical attention. However, they are often followed by delayed
reactions such as sudden, possibly fatal collapse 12 to 72 hours after
exposure.
12.36. A
superficial respirator program might lull employees into a false sense of
security. Later, if a real respiratory
problem develops, the partial program will be inadequate to deal with the
problem, and workers will not be protected.
Bad habits such as negligent maintenance, inadequate fit testing, or
improper equipment usage could be present without consequence, if the program
is not really needed to begin with. A
feeling of complacency toward the use of respirators can be engendered by the
use of such equipment when it is not really needed.
12.37. “Double-block-and-bleed”
refers to a procedure for isolation of a confined space which closes two valves
in series in a pipe leading into the space, and in addition opens a small bleed
valve in the pipe in the space between the two major valves. The bleed valve allows the escape of any
fluids that might accumulate due to high pressure differential on the primary
major valve. The secondary major valve
thus has little or no pressure differential across it and can achieve a
positive closure.
RESEARCH
EXERCISES
12.38. At
least one accident has been reported in the area of working in the confined
space of a service pit for a display waterfall (fountain) in a shopping
mall. An employee lost consciousness
when he descended seven feet to the bottom of a service pit to adjust valves
for the fountain. A companion worker
entered the pit to rescue the first worker and also lost consciousness. A security guard and a passerby tried to
assist but became dizzy. The fire
department was summoned to the scene and both employees were revived and were
treated and released. OSHA investigated
four such service pits in this shopping mall and found three of the four had
oxygen concentrations of less than the minimum acceptable 19.5 percent. In addition, carbon dioxide readings were
more than double the OSHA PEL. Similar
problems have been studied by NIOSH.
References: This story was first found on the Internet at
the Uni-Hoist Newsletter. Uni-Hoist is a
manufacturer of confined space entry equipment. The URL used to find this data
on the Internet was:
http://www.cdnsafety.com/unihoist.html
This URL may no longer be available. Other articles describing confined space
hazards may be found at http://www.cdnsafety.com/articles.htm
Data on this accident may also be
available on the OSHA website. OSHA changes the organization of the website
from time to time. At the time of this printing in 2003, a description of this
accident was found in a Hazard Information Bulletin, dated June 13, 1996, by
doing a search on the term “waterfall” in the OSHA website search facility
entitled “Find it! In DOL”
12.39. “Air-off”
conditions represent a real hazard, especially when workers are in a dangerous
atmosphere. When sudden air-off occurs,
workers are afraid to remove the suit top or helmet in a contaminated
atmosphere environment, so they try to quickly escape to a safe area before
removing the headgear. Unfortunately,
oxygen-deficiency becomes a more serious hazard than the contaminated
atmosphere, in many cases. Tests have
shown that oxygen levels can be depleted inside the suit to a dangerous 16
percent in only 40 seconds! The
situation can deteriorate into a life-threatening situation very quickly. Besides escape situations, simple donning and
doffing of air-supplied suits during training exercises without turning on the
supplied air can result in dangerous oxygen-deficiency. Especially because of the escape hazard, the
Department of Energy (DoE) has issued directives that workers should be trained
to give precedence to preventing oxygen-deficient atmosphere inside the suit at
the expense of sacrificing contamination control.
Original reference for this
information: “Potential Oxygen
Deficiency While Wearing Air-Supplied Suits,” DOE/EH-0414, Issue No. 96-1,
April, 1996.
12.40. The
problem is at least as prevalent in grain bins as in sand bins. Many fatalities have been reported.
Suffocation in flowing grain is the most common cause of death associated with
grain storage structures in the
References:
1.
Loewer, Otto J., and David H. Loewer, “Suffocation Hazards in Grain
Bins,”
2. Baker DE. Safe storage and
handling of grain.
3. Aherin RA, Schultz L. Safe
storage and handling of grain. In:
4. Snyder KA, Bobick TG, Hanz JL,
Myers JR. Grain-handling fatalities in production agriculture, 1985-1989.
Presented at the 1992 International Winter Meeting, Division of Safety
Research, National Institute for Occupational Safety and Health.
5. “Suffocations in Grain Bins --
October 4, 1996/Vol. 45/No. 39
12.41. A
good comparison of various hazards for methane can be found in the Preamble to
the “Permit-Required Confined Space Entry” standard, found in the Federal
Register and the OSHA website. The
following is quoted from that preamble:
“Some chemical substances present
multiple atmospheric hazards, depending on their concentration. Methane, for
example, is an odorless substance that is nontoxic and is harmless at some
concentrations. Methane, however, can displace all or part of the atmosphere in
a confined space(1); and the hazards presented by such displacement can vary
greatly, depending on the degree of displacement. With only 10 percent
displacement, methane produces an atmosphere which, while adequate for
respiration, can explode violently. By contrast, with 90 percent displacement,
methane will not burn or explode, but it will asphyxiate an unprotected worker
within about 5 minutes.
__________
Footnote(1) Methane is lighter than air when both are at the same
temperature (the normal case), and
the configuration of some confined
spaces can trap accumulating
methane at "ceiling"level. On the other
hand, in the unlikely event that
liquified methane is released into the
atmosphere of a confined space,
the methane released would be heavier than air and would displace the air from
the "ground" level up.
12.42. The best source for finding the
requested background information on any promulgated standard is in the preamble
to the standard published in the Federal Register by OSHA at the time of
promulgation. The following is quoted
from the Preamble to the “Permit-Required Confined Space Entry” standard, found
in the Federal Register and the OSHA website:
a.
NIOSH definition of “confined space”:
“a space which by design has limited openings for entry and exit,
unfavorable natural ventilation which could contain or produce dangerous air contaminants,
and which is not intended for continuous employee occupancy.”
b.
Three classes of confined spaces, as prescribed by NIOSH:
1.
Class A – immediately dangerous to life or health
2.
Class B – dangerous
3.
Class C – confined spaces in which the potential hazard would not
require any special modification of the work procedure.
c.
Three employer “problems” associated with confined spaces were published
in an “Alert” titled “Request for Assistance in Preventing Occupational
Fatalities in Confined Spaces” (NIOSH, January, 1986), as follows:
1.
recognizing confined spaces
2.
testing, evaluating, and monitoring confined space
3.
developing and implementing rescue procedures.
d. In January 1986, NIOSH
published an "Alert" titled "Request for Assistance in
Preventing Occupational Fatalities in Confined Spaces" (Ex. 13-16). The
Alert described the circumstances under which 16 workers died (14 of them due
to atmospheric hazards) in confined space incidents. NIOSH focused on problems
employers have in three areas: (1) recognizing confined spaces; (2) testing,
evaluating, and monitoring confined space atmospheres; and (3) developing and
implementing rescue procedures. It was noted, for example, that "[m]ore
than 60% of confined space fatalities occur among would-be rescuers." The
Alert recommended that employers protect employees who enter confined spaces by
implementing measures similar to those presented in the 1979 Criteria Document.
e. According to the January 1986,
NIOSH-published "Alert" titled "Request for Assistance in
Preventing Occupational Fatalities in Confined Spaces": "[more than
60% of confined space fatalities occur among would-be rescuers." (found in
the Preamble to the “Permit-Required Confined Space Entry” standard, published
in the Federal Register and the OSHA website)
12.43. From
the OSHA website it can be determined that the general standard for confined
space entry is OSHA standard 29CFR1910.146 – “Permit-Required Confined Space
Entry.” Section a. (Scope and application)
specifically excludes agriculture, construction, and shipyard employment from
coverage under the standard. The
preamble to the standard explains that these areas are covered under other
standards. The preamble also contains discussion and arguments over the scope
of the standard. The telecommunications
industry argued that it should be excluded, but an exclusion for the
telecommunications industry does not appear in the Section a. Scope and
application paragraph of the standard.
12.44. Specific
information on the telecommunications industry was included in the Preamble to
the “Permit-Required Confined Space Entry” standard published in the Federal
Register and the OSHA website, as follows:
Estimate of the number of
telecommunications manholes in the United States: 1,000,000
It has been argued that
telecommunications manholes should be excluded from coverage as “confined
spaces” in the general OSHA standard.
Quoting testimony from the telecommunications industry in the preamble:
“there are huge differences in
confined spaces in chemical and manufacturing plants in telecommunication
manholes. First and foremost, the inherent hazard of telecommunications
manholes is significantly less. Telecommunication manholes are not designed to
contain any kind of chemical or hazardous substance. They do not contain a
residual hazardous atmosphere. Telecommunication manholes exist to provide
access to underground telephone cables and conduits during splicing, testing,
maintenance and air pressurization operations. In most cases, the atmosphere in
telecommunication manholes is the same as that outside the manhole.
Secondly, telecommunications
manholes are located in and around public roads and rights-of-way all over the
United States………. While there is no question as to the need for special
procedures to protect employees who enter telecommunications manholes, to be
effective in saving lives, these procedures must reflect the difficulties
inherent in having such a large, widely-scattered workforce. Telecommunications
manhole entries are routine, performed on a daily basis and, based on data in
OSHA's current record, done safely.
The third major difference is that
entry into telecommunications manholes is already regulated by OSHA.”
According to the preamble: “GTE has about 8,700 employees who will enter
telecommunications manholes approximately 320,000 times a year.” (This is interpreted to be a total figure. Dividing 320,000 by 8,700 yields an average
per employee of approximately 36 or 37 times per year.
According to the preamble: “Entry
into telecommunications manholes and unvented cable vaults is currently
regulated by Section 1910.268(o)(2).”
12.45. The NCM database can be used to perform
a keyword search on the term *respiratory
protection*. Such a search returns a long list of citations, the vast
majority of which are in the general respiratory protection standard, OSHA
standard 29CFR1910.134. Some other respiratory provisions of specialized
standards are also included in the list, especially in the standards included
in the “standards completion project” (refer to Table 9.1 in the text, page
187). The total number of citations listed in the NCM database for the term
“respiratory protection” is 9101. The corresponding search using the “serious
violations” search capability reveals a total of 4206 citations, or 4206/9101 =
46 % of the total. A search of the database can be focused on general personal
protective equipment by using the keyword search term *personal protective equipment*. Such a search, using the NCM
database, shows a total of 4927 citations. Doing a similar search by “serious
violations” a total of 3285 is shown, or 3285/4927 = 67 % of the total. So,
comparing the terms “respiratory protection” and “personal protective equipment”
as they appear in standards cited by OSHA during the fiscal year reported in
the NCM database, standards containing the term “respiratory protection” have
resulted more citations, but a greater percentage of the standards containing
the term “personal protective equipment” have been in the “serious violation”
category. Both terms are involved in frequent citation activity, and a large
percentage of citations for both of these terms are designated as “serious.”
12.46. Using the NCM database keyword searching
capability, a search for the term *medical
services and first aid* results in a printout of several standards
containing this word group. The most heavily cited standard is OSHA standard
29CFR1910.151(c). The OSHA website reveals that this standard is the general
requirement for medical services and first aid. If all provisions containing
the word group “medical services and first aid” are included, the NCM database
shows a total of 1887 citations for the fiscal year. Another search for the same
word group, using the “serious violations” option of the NCM database keyword
search capability, a total of 1283 citations is shown. Thus the percentage of
total alleged violations that are in the “serious” category is 1283/1887 =
approximately 68 %. Apparently, OSHA takes the subject of “medical services and
first aid” quite seriously.