Industrial Hygiene: Toxic Substances and Confined Spaces

1
Chapter 20

• Industrial Hygiene Toxic Substances and Confined
  Spaces

2
Major Topics

• Hazards in the workplace
• OSH Act and industrial hygiene
• Airborne contaminants
• Asbestos hazards
• Sick building syndrome
• NIOSH and industrial hygiene
• OSHA confined spaces standard

3
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.

4
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

5
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.

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OSHA requirements relating to industrial hygiene

• 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

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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.

8
Routes of entry for toxic agents

• The most common routes of entry for toxic agents
  are inhalation, absorption, injection, and
  ingestion.

9
Airborne contaminants dust, fumes, smoke, mists,
and gases

• 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.

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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.

11
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.

12
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.

13
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.

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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.

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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.

16
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

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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.

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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.

19
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.

20
Toxic Substance

• A toxic substance is one that has a negative
  effect on the health of a person or animal.

21
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

22
Common routes of entry of toxic substances

• The most common routes of entry of toxic
  substances are inhalation, absorption, injection
  and ingestion.

23
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
• where
• C concentration
• T duration (time) of exposure
• K constant

24
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.

25
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.

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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.

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Carcinogen

• A carcinogen is any substance that can cause a
  malignant tumor or a tissue that may become
  cancerous.

28
OSHA chemical process standard, EPA clean air
act, and SARA

• 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.

29
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.

30
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.

31
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.

32
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 buildings ability to
  eliminate contaminated air and bring in fresh air
  are ventilation, air infiltration rates, airflow
  rates in ducts, airflow patterns, and fume
  exhaust.

33
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).

34
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.

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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.
• OSHAs 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.

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Home work

• 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 ACMs (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 OSHAs Hazard
  Communication Standard.