Transcript Chapter 14

Chapter 20
Industrial Hygiene: Toxic
Substances and Confined Spaces
Major Topics
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Hazards in the workplace
OSH Act and industrial hygiene
Airborne contaminants
Asbestos hazards
Sick building syndrome
NIOSH and industrial hygiene
OSHA confined spaces standard
Industrial Hygiene
• Industrial hygiene is a safety and health
profession that is concerned with
predicting, recognizing, assessing,
controlling, and preventing environmental
stressors in the workplace that can cause
sickness or serious discomfort to workers.
• Common stressors include gases, fumes,
vapors, dusts, mists, noise, and radiation.
Responsibilities of the modern
industrial hygienist
• Code of ethics of the American Academy of Industrial
Hygiene:
• To ensure the health of employees
• To maintain an objective approach in recognizing,
assessing, controlling and preventing health hazards
regardless of outside pressure and influence.
• To help employees understand the precautions that they
should take to avoid health problems.
• To respect employees honesty in matters relating to
industrial hygiene
• To make the health of employees a higher priority than
obligations to the employer
Role of the safety and health
professional
• In companies that employ specialists, their
recommendations are used by safety and health
professionals to develop, implement, monitor,
and evaluate the overall safety and health
program.
• If specialists are not employed, safety and health
professionals are responsible for seeking the
advice and assistance necessary to predict,
recognize, assess, control, and overcome
environmental stressors that may cause
sickness or serious discomfort to employees.
OSHA requirements relating to
industrial hygiene
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Use of warning labels and other means to make employees aware of
potential hazards, symptoms of exposure, precautions, and
emergency treatment
Prescription of appropriate personal protective equipment and other
technological preventive measures [29CFR 1910.133 and 1910.134
subpart I]
Provision of medical tests to determine the effect on employees of
exposure to environmental stressors
Maintenance of accurate records of employee exposures to
environmental stressors that are required to be measured or
monitored
Accessibility of monitoring tests and measurement activities to
employees
Availability of monitoring tests and measurement activity records to
employees on request
Notification of employees who have been exposed to environmental
stressors at a level beyond the recommended threshold and corrective
action being taken
Typical categories of hazard in the
workplace
• Categories: chemical, physical, biological and
ergonomic.
• Chemical hazards: include mists, vapors, gases, dusts,
and fumes.
• Physical hazards: include noise, vibration, extremes of
temperature, and excessive radiation.
• Biological hazards: come from molds, fungi, bacteria,
and insects. Bacteria may be introduced in the
workplace through sewage, food waste, water or insect
droppings.
• Ergonomic hazards: poorly designed workstations and
tools, conditions that put workers in awkward positions or
impair their visibility.
Routes of entry for toxic agents
• The most common routes of entry for toxic
agents are inhalation, absorption,
injection, and ingestion.
Airborne contaminants: dust,
fumes, smoke, mists, and gases
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Dusts are various types of solid particles that are produced when a given type
of organic or inorganic material is scrapped, sawed, ground, drilled, handled,
heated, crushed or otherwise deformed. The degree of the hazard depends on
the toxicity of the parent material and the size and level of concentration of the
particles.
Fumes: Welding, heat treating, and metalizing all involve the interaction of
intense heat with the parent material, which results in tiny particles of the
parent material which can be inhaled.
Smoke: Smoke is the result of incomplete combustion of carbon material. Tiny
soot or carbon particles remain that can be inhaled.
Aerosols: are liquid or solid particles that are so small that they can remain
suspended in air long enough to be transported over a distance. They can be
inhaled.
Mists: are tiny liquid droplets suspended in the air. Mists are formed when
vapors return to a liquid state through condensation and when the application
of a sudden force or pressure turns a liquid into particles.
Gases: become hazardous when they fill a confined unventilated space. The
mist common forms of gases in industrial settings are from welding and the
exhaust from internal combustion engines.
Remove or contain asbestos
• Following factors should be considered:
• Is there evidence that the ACM (asbestos containing
material) is deteriorating? What is the potential for further
deterioration?
• Is there evidence of physical damage to the ACM? What
is the potential for future damage?
• Is there evidence of water damage to the ACM or
spoilage? What is the potential for future damage or
spoilage?
• The most widely used methods for dealing with asbestos
are removal, enclosure and encapsulation.
ANSI Z9.8 (indoor air
quality/HVAC)
• General Coverage: ANSI Z9.8 is very specifically written to apply
primarily to office space. It applies specifically to employee
occupancies in non industrial spaces including general office
spaces, commercial operations, and office spaces with industrial
facilities.
• Application flexibility: When the provisions of ANSI Z9.8 conflict with
other standards the more stringent standard is to take precedence.
• Acceptable air quality: Employers may establish ceiling limits (e.g. if
more than 2% of the employees complain about air quality problems
the ceiling limit has been reached).
• Tobacco smoke: The standard requires that employers evaluate
smoking in the workplace and apply whatever management controls
are appropriate.
Asbestos: removal, enclosure and
encapsulation
• Removal: known as asbestos abatement. The area in question must
be completely enclosed in walls of tough plastic. The enclosed area
must be ventilated by High efficiency particle absolute (HEPA)
filtered negative air machines. The ACM (asbestos containing
material) must be covered with a special liquid solution to cut down
on the release of asbestos fibers. The ACM must be placed in leak
proof containers for disposal.
• Enclosure: use HEPA filtered negative air machines in conjunction
with drills or any other tools that may penetrate or otherwise disturb
ACMs. Construct the enclosing walls of impact resistant air tight
material. Post signs indicating the presence of ACMs within the
enclosed area. Note the enclosed area on the plans of the building.
• Encapsulation: of asbestos involves spraying the ACMs with a
special sealant that binds them together thereby preventing the
release of fibers. The sealant should harden into a tough impact
resistant skin. This approach is generally used on acoustical plaster
and similar materials.
Medical examinations for
employees who handle ACMs
• Medical examinations conducted at least annually should
be required for employees who handle ACMs. These
examinations should include front and back chest X-rays
that are at least 7 “ by 14”. The examination should also
test pulmonary function, including forced vital capacity
and forced expiratory volume at one second.
• Medical records on such employees should be kept for
at least 20 years. They should contain the complete
medical history of the employee. These records must be
made available on request to employees, past
employees, health care professionals, employee
representatives, and OSHA personnel.
Exposure thresholds: time weighted average, short
term exposure limit, and exposure ceiling
• Threshold Limit Value-Time weighted average (TLV-TWA): The time
weighted average for a conventional 8 hour work day and 40 hour
work week for a given substance to which it is believed that nearly
all workers may be repeatedly exposed on a daily basis without
suffering ill effects. For example the TLV-TWA for liquefied
petroleum gas is 1000 parts per million (ppm).
• Threshold Limit Value-Short term exposure limit (TLV-STEL): A
STEL is defined as a 15 minute TWA exposure that should not be
exceeded at any time during the work day period. It should not
occur more than 4 times in the day (with at least 60 minutes
between exposures). For example the TVL-STEL for isopropyl ether
is 310 ppm.
• Threshold Limit Value-Ceiling (TLV-C): The concentration of a given
substance that should not be exceeded at any point during an
exposure period.
Evaluating hazards in the
workplace
• For hazard evaluation the following
considerations are important:
• The nature of the material or substance
involved, the intensity of the exposure, and the
duration of the exposure.
• Key factors to consider are how much exposure
is required to produce injury or illness; the
likelihood that enough exposure to produce
injury or illness will take place; the rate of
generation of airborne contaminants; the total
duration of the exposure; and the prevention and
control measures used.
Generic prevention and control
strategies
• Most prevention and control strategies can
be placed in one of the following 4
categories:
• Engineering controls
• Ventilation
• Personal protective equipment
• Administrative controls
Prevention/control strategy: engineering controls,
ventilation, personal protective equipment
• Engineering Controls: replacing toxic material with one that is less
hazardous or redesigning a process to make it less stressful or to
reduce exposure to hazardous material or conditions, isolating
hazardous process to reduce the number of people exposed to it
and introducing moisture to reduce dust.
• Ventilation: exhaust ventilation involves trapping and removing
contaminated air. Used with such processes as abrasive blasting,
grinding, polishing, buffing, and spray painting or finishing. Dilution
ventilation involves simultaneously removing and adding air to dilute
a contaminant to acceptable levels.
• Personal protection: Personal protective equipment (PPE) imposes
a barrier between the worker and the hazard. Typical equipment
include safety goggles, face shields, gloves, boots, earmuffs, ear
plugs, full body clothing, and respirators.
• Specially designed eyewash and emergency wash stations (fig 20-8,
9, 10) should be readily available and accessible in any work setting
where contaminants may be present.
Worker self protection strategies
• Know the hazards in your workplace: take time to identify all
hazardous material and conditions in your workplace and know the
safe exposure levels of each.
• Know the possible effects of hazards in your workplace: Typical
effects of workplace hazards include respiratory damage, skin
disease and irritation, injury to the reproductive system, and damage
to the blood, lungs, central nervous system, eyesight and hearing.
• Use PPE properly: Choosing the right equipment, getting a proper
fit, correctly cleaning and storing equipment, and inspecting
equipment regularly for wear and damage.
• Understand and obey safety rules: Read warning labels before
using any contained substance, handle materials properly, read and
obey signs, and do only authorized work.
• Practice good personal hygiene: Wash thoroughly after exposure to
a hazardous substance, shower after work, wash before eating, and
separate potentially contaminated work clothes from others before
washing them.
NIOSH and Industrial Hygiene
• The National Institute of Safety and Health [NIOSH] is
part of the Department of Health and Human Services
[HHS].
• The main focus of the agency is on toxicity levels and
human tolerance levels of hazardous substances.
• NIOSH prepares recommendations for OSHA standards
dealing with hazardous substances and NIOSH studies
are made available to employers.
• Their continually updated list of toxic materials and
recommended tolerance levels are extremely helpful to
industrial hygienists concerned with keeping the
workplace safe.
Toxic Substance
• A toxic substance is one that has a
negative effect on the health of a person
or animal.
Effect of a toxic substance
• Toxic effects are functions of several
different factors including the following:
• Properties of the substance
• Amount of the dose
• Level of exposure
• Route of entry
• Resistance of the individual to the
substance
Common routes of entry of toxic
substances
• The most common routes of entry of toxic
substances are inhalation, absorption,
injection and ingestion.
Dose-response relationship
• A dose of toxic substance can be expressed in a
number of different ways depending on the
characteristic of the substance: amount per unit
of body weight, amount per body surface area,
or amount per unit of volume of air breathed.
• Olishifski expressed the dose response
relationship mathematically as : C * T = K
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• C = concentration
• T = duration (time) of exposure
• K = constant
Dose threshold, lethal dose, and
lethal concentration
• Dose threshold: is the minimum dose required to
produce a measurable effect.
• Lethal dose: is the dose that is highly likely to
cause death.
• Lethal concentration: of an inhaled substance is
the concentration that is highly likely to result in
death. With inhaled substances the duration of
exposure is critical because the amount inhaled
increases with every unprotected breath.
Acute and chronic effects and
exposures
• Acute effects and exposures involves a sudden
dose of a highly concentrated substance. They
are usually the result of an accident that result in
an immediate health problem ranging from
irritation to death.
• Chronic effects and exposures involve limited
continual exposure over time. Consequently the
associated health problem develops slowly.
• Fig 20-3 page 439: selected toxic substances
and the organs they affect most.
Classification of airborne toxics
• Airborne toxic substances are classified according to the
type of effect they have on the body.
• The primary classifications are:
• irritants - cause irritation to skin, eyes, nose, mouth,
throat, and upper respiratory tract.
• asphyxiants - disrupt breathing so severely that
suffocation results.
• narcotics/anesthetics - can inhibit normal operation of
central nervous system.
• With all airborne contaminants concentration and
duration of exposure are critical concerns.
Carcinogen
• A carcinogen is any substance that can
cause a malignant tumor or a tissue that
may become cancerous.
OSHA chemical process standard,
EPA clean air act, and SARA
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OSHA chemical process standard: The standard requires chemical
producers to analyze their processes to identify potentially hazardous
situations and to assess the extent of the hazard. Having done so they
must accommodate this knowledge in their emergency response plans
and take action to minimize the hazards. Specific additional
requirements include: compiling process safety information,
maintaining safe operating procedures, training and educating
employees, maintaining equipment, conducting incident
investigations, developing emergency response plans, and
conducting safety compliance audits.
EPA clean air act (1990): The law is designed to reduce air pollution –
in the form of hazardous air pollutants, acid rain, and smog – by 56
billion pounds per year. This includes a 75% reduction in air toxics, a
50% cut in acid rain, and a 40% decrease in smog.
Superfund Amendments and Reauthorization Act (SARA): This law is
designed to allow individuals to obtain information about hazardous
chemicals in their communities so that they can protect themselves in
case of emergency. It applies to all companies that use, make,
transport, or store chemicals.
Threshold limit value (TLV)
• Threshold limit values: refer to airborne
concentrations of substances and represent
conditions under which it is believed that nearly
all workers may be repeatedly exposed day after
day without adverse effect.
• Threshold limits are based on the best available
information from industrial experience, from
experimental human and animal studies, and
when possible a combination of the three.
Time weighted average and ceiling
• The time weighted average for a
conventional 8 hour work day and 40 hour
work week for a given substance to which
it is believed that nearly all workers may
be repeatedly exposed on a daily basis
without suffering ill effects.
• Ceiling: the concentration of a given
substance that should not be exceeded at
any point during an exposure period.
NIOSH categories of respirators
• Class N (not oil resistant): respirators may be used only in
environments that contain no oil based particulates. They may be
used in atmospheres that contain solids or non oil contaminants.
• Class R (Oil resistant): respirators may be used in atmospheres
containing any contaminant. However the filters in Class R
respirators must be changed after each shift if oil based
contaminants are present.
• Class P (oil proof): respirators may be used in any atmosphere
containing any particulate contaminant.
• If there is any question about the viability of an air filtering respirator
in a given setting, employees should use air supplying respirators.
Air from the air is completely blocked out, and fresh air is provided
via a self contained breathing apparatus.
Sick building syndrome
• A sick building is one that makes people sick because it
has become infested with mold, mildew, spores, and
other airborne micro organisms.
• Poor indoor air quality (IAQ) can cause a variety of
health problems ranging from the temporary to the long
term.
• One of the keys in preventing sick building syndrome is
air exchange.
• Important factors in a building’s ability to eliminate
contaminated air and bring in fresh air are: ventilation, air
infiltration rates, airflow rates in ducts, airflow patterns,
and fume exhaust.
OSHA confined space standard
• The OSHA confined space standard (29 CFR 1910.146)
mandates that entry permits be required before
employees are allowed to enter a potentially hazardous
confined space.
• Before the permit is issued a supervisor, safety or health
professional, should do the following: shut down
equipment/power (locked/tagged), test the atmosphere
(19.5 to 23.5% oxygen), ventilate the space, have rescue
personnel stand by, maintain communication, and use a
lifeline (can pull an unconscious employee out of a
confined space).
OSHA hazard communication
standard (29 CFR 1910.1200)
• Any organization that uses hazardous
material in the workplace is required to
fully inform employees and on-site
contractors of the hazards and to provide
training concerning the safe handling,
storage, and use of the materials.
Summary
• Common airborne contaminants are dusts, fumes, smoke, mists,
gases, and vapors.
• Asbestos has been tied to respiratory cancer.
• The American National Standards Institute (ANSI) developed its
own national air quality standard (ANSI z9.8).
• The National Institute of Occupational Safety and Health (NIOSH) is
part of the Department of Health and Human Services. It conducts
research and education in human tolerance levels to toxic materials.
• A confined space management policy should include:
administration, controls, training, and work team requirements.
• Material Safety Data Sheets (MSDS) are an excellent source of
information for safety and health professionals.
• OSHA’s Hazard Communication Standard (29 CFR 1910.1200)
requires organizations to inform employees and contractors of the
presence of hazardous substances in the workplace and provide
safe use training.
Home work
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Answer questions 4, 9, 11, 16, 17, 26, 29, 30, 31, and 33 on page 477.
4. List 5 OSHA requirements relating to industrial hygiene.
9. Summarize the various elements of ANSI Z9.8 (indoor air quality/HVAC).
11. What type of medical examinations should be required of employees
who handle ACM’s (Asbestos Containing Materials).
16. Explain 5 self protection strategies that employees can use in the
workplace.
17. How does NIOSH relate to industrial hygiene?
26. Describe the basic provisions of the following standards: OSHA
Chemical Process Standard, EPA Clean Air Act, and SARA.
29. Explain the 3 NIOSH categories of respirators.
30. What is sick building syndrome?
31. Explain the major tenets of the OSHA Confined Space Standard.
33. Summarize the requirements of OSHA’s Hazard Communication
Standard.