Airborne Hazards

1
Airborne Hazards

• IENG 341
• Carter J. Kerk, PhD, PE, CSP, CPE
• Industrial Engineering Department
• South Dakota School of Mines
• Spring 2008

2
Chapter 4 Assignment

• Read Chapter 4
• HW4
• Critical Thinking Questions
• P. 97
• 1-6
• Due?

3
Outline

1. Anatomy and function of the lungs
2. Airborne hazardous materials
3. Occupational diseases associated with airborne
   particulates
4. Oxygen-deficient atmospheres

4
Introduction

• Route of entry Airborne hazards are the most
  serious concern
• Processes welding, grinding, spraying, hot
  processes, engine exhausts
• Pollen, spores
• Lungs efficient transfer of gases in and out of
  the body
• But also provide a route of entry for hazards

5
Anatomy Function of the Lungs

• Regions of the respiratory tract
• Upper (nasopharyngeal)
• Middle (tracheobronchial)
• Lower (distal)
• ACB Plates 91-97

6
Upper (Nasopharyngeal)

• Head, nose, nasal passages, sinuses, mouth,
  tonsils, epiglottis, back of throat
• Lined with mucous membrane
• Moist, sticky substance captures materials
• Many small hairs
• Help to trap particles

7
Middle (Tracheobronchial)

• Trachea (windpipe), bronchi
• Rings of cartilage and muscle
• Cartilage provides structural support
• Muscles contract to help force air
• Coughing, sneezing
• Lined with mucous membrane and hairs (cilia)
• Cilia move like waves to push mucus and particles
  upward
• Cigarette smoking can paralyze the cilia
• Particle-laden mucus is removed by coughing,
  expectorating, or swallowing

8
Lower (Distal)

• Bronchi split (bifurcate) repeatedly into two
  smaller passages (17 times, 217 131,072) called
  bronchioles
• Diameters decrease accordingly
• Bronchioles end in microscopic sacs called
  alveoli (site of gas exchange)
• Alveolar membrane is one cell thick
  (pneumocytes), surrounded by capillaries
• Passive diffusion

9
(No Transcript)
10
(No Transcript)
11
(No Transcript)
12
Definition Microns (Micrometer)

• One thousandth of a millimeter
• 0.001 mm 1 mm
• Greek letter, m
• Useful in discussion of the size of inhaled
  particles
• Visible to human eye
• gt 100 mm 0.1 mm 0.01 cm
• Human hair diameter
• 5 500 mm 0.005 0.5 mm

13
Protective Mechanisms of the Respiratory Tract

• Larger particles (gt10 mm)
• Removed in nose and upper airways
• 5 10 mm
• Captured in tracheal region
• 3 5 mm
• Contact mucus lining in tracheal or bronchi
• 0.5 3 mm
• Can reach alveolar region, but few do

14
Capture of particles

• Mucus (moist, sticky) linings
• Tortuous pathway
• Multitude of branches and splits
• Large surface area of the route
• Once particles are captured in mucus, they are
  removed by the mucociliary elevator or ladder
• Cough reflex

15
(No Transcript)
16
Protection in the Alveolar Region

• Primary defense macrophages (specialized white
  blood cells)
• Engulf foreign objects and attempt to dissolve
  them
• The smallest of particles may pass through cell
  membranes and lodge between cells (interstitial
  space)

17
Airborne Hazardous Materials

• Aerodynamic Diameter
• Useful for comparing particles with irregular
  shapes (dusts, fibers, etc.) to particles with
  regular shapes (droplets, mists, etc.)
• The diameter of a reference spherical particle
  with a unit density of one (1) that has the same
  settling velocity as the contaminant particle

18
(No Transcript)
19
Classes of Airborne Materials

• Particulates / aerosols
• Solid particles, dusts, fibers, mists, droplets,
  fumes
• Gases / vapors
• Gaseous contaminants, vapors
• Oxygen-deficient atmospheres
• lt 19.5 oxygen
• Combination
• Any combination of particulates and/or gases,
  including oxygen-deficient atmospheres

20
Particulate contaminants

• Particulates and aerosols
• Individual or discrete masses
• (Not gases or vapors)
• Aerosols
• Liquid droplets or solids that are suspended in
  air for an extended period of time
• Dusts, mists, fumes

21
Dusts (particulates/aerosols)

• Aerosols composed of dry particles, fibers,
  powders
• Naturally occurring or from blasting, mining,
  grinding, polishing, crushing, etc.
• Concerned with lt 10 mm
• Irritation, allergic response, various diseases,
  cancer, explosions
• Silica, coal, grains, sawdust

22
Mists (particulates/aerosols)

• Airborne droplets from processes involving
  liquids (sprays, coolants, cutting fluids,
  paints, solvents, pesticides, etc.)
• Air (or other gas) is introduced into a liquid
  (usually under pressure), causing the liquid to
  break apart (aerolize)
• Surface tension between molecules causes them to
  stick together and form droplets
• Can cause bacteria to become airborne
• Hazards depends on size, reactivity, solubility,
  toxicity
• Responses irritation, inflammation, stimulation
  of mucus production, pulmonary edema (lung
  fluid), allergic or sensitization response

23
Fumes (particulates/aerosols)

• Produced when metals are heated (gt 2000 C) to
  the point they become a vapor or gas
• The hot gas cools once airborne, then condenses
  to form small particles
• Diameters 0.1 100 mm
• Processes welding, cutting torch, sometimes
  buffing/grinding
• CO is not a fume airborne phase is a gas
• Gasoline is not a fume airborne phase is a vapor

24
Classes of Airborne Materials

• Particulates / aerosols
• Solid particles, dusts, fibers, mists, droplets,
  fumes
• Gases / vapors
• Gaseous contaminants, vapors
• Oxygen-deficient atmospheres
• lt 19.5 oxygen
• Combination
• Any combination of particulates and/or gases,
  including oxygen-deficient atmospheres

25
Gases

• Air nitrogen, oxygen, argon, carbon
  dioxide,water
• Oxygen Carbon Dioxide exchange
• Damaging gases carbon monoxide, acetylene,
  ammonia, chlorine, hydrogen fluoride, hydrogen
  sulfide, sulfur dioxide

26
(No Transcript)
27
Vapors

• Gaseous phase of liquids
• Tendency of a liquid to change to a gas depends
  on its vapor pressure (how quickly it will
  evaporate and thus breathable)
• Higher vapor pressure (faster evaporation)
• High VP presents toxicity, asphyxiation,
  flammable/explosive mixtures

28
Effects of Inhaled Materials

• Airborne toxins
• Local effects on tissues
• Ammonia irritation in respiratory tract
• Systemic effects through blood transport
• Carbon tetrachloride (liver)
• Solubility
• More soluble upper respiratory tract, moist
  tissue around eyes ammonia
• Less soluble penetrate to middle and lower
  respiratory tract phosgene gas

29
Size-selective Sampling

• Recall the relationship between particle size and
  site deposition?
• Thus size-selective sampling becomes important
• ACGIH has defined three ranges (or fractions)
• Inhalable
• Thoracic
• respirable

30
Size-Selective Sampling
31
Size-Selective Sampling

• Some OSHA PELs are established for the respirable
  fraction
• Example crystalline silica
• Table Z-1, Silicon
• Total Dust, 15 mg/m3
• Respirable fraction, 5 mg/m3

32
Occupational Diseases Associated with Airborne
Particulates

• Pneumoconiosis
• Physiological Responses
• Mineral Fibers and Other Fibers
• Metals
• Organic Particles

33
Pneumoconiosis

• Reaction of lung tissue to the presence of dust
• Inhaled dust may deposit in the lungs, be
  detectable with x-rays, but with no ill effects
• Some dusts cause scarring and damage leading to
  severe impairment
• Silicosis pneumoconiosis caused by inhaling
  silica dust
• Asbestosis - asbestos
• Berylliosis - beryllium
• Aluminosis - aluminum

34
Physiological Responses Associated with Inhaled
Dust

• Increased production of mucus
• Engulfment of particles by macrophages
• Inflammation of tissues
• Edema (swelling)
• Formation of fibrous tissues (reticulin,
  collagen), usually benign
• Reticulin immature red blood cells that dont
  mature
• Siderosis - iron oxide dust in lungs, reddish
  discoloration, benign

35
Silicosis

• scarring of lungs from crystalline silica
• reticulin nodules build up when macrophages
  engulf the silica particles
• When macrophage dies, it released the silica
  particle and another macrophage engulfs it
• Endless cycle which impairs lung function
• May lead to hypertension (high blood pressure)
  and an enlarged heart
• May mask the presence of tuberculosis or
  pneumonia
• Silicon dioxide, SiO2 quartz, tridymite,
  cristobalite, coesite
• Must evaluate respirable fraction
• Study Table Z-3

36
Mineral Fibers and Other Fibers

• Asbestos (best known)

37
Metals

• Inhalation of metal fumes
• One of the oldest known occupational diseases
• Agricola, etc.
• Aluminum, Lead, Cadmium, Chromium

38
Metals

• Inhalation of metal fumes or dust (from grinding,
  machining, sawing, sanding)
• Metal oxides metal atoms combined with oxygen
  atoms can also be inhaled
• Iron oxide rust
• Metals differ in their site of effect (see next
  slide)

39
(No Transcript)
40
Metal Fume Fever

• Inhalation of metal fumes during welding
• Flu-like symptoms that may be mistaken for the
  flu
• Fever, nausea, coughing, wheezing, muscle aches
• Cause could be a single metal or a combination of
  several

41
Aluminum

• Inhalation during smelting, refining,
  metalworking
• Aluminum and its oxides used in paints, coatings,
  ammunition, explosives, abrasives, ceramics
• Irritants to respiratory system
• Acute exposure alveolar edema
• Chronic exposure interstitial fibrosis,
  emphysema (Shavers disease, bauxite lung)
• Particle damage to cornea
• Aluminum is not regulated by OSHA except as a
  nuisance dust

42
Lead

• Frequently encountered
• Exposure the lead fume or lead oxide (as a dust)
• Mining and smelting
• Cutting and welding on surfaces covered with
  lead-containing paints
• Manufacture / recycling of lead-containing
  batteries
• Production of lead-containing paints / coatings

43
Lead Paints / Coatings

• Some legislation requires identification of
  lead-based paint in residential buildings
• Hazard to occupants and workers who remove it
• Children are particularly susceptible

44
Lead

• 90 of lead that enters the body accumulates in
  the bones
• Biological half-life of 10-20 years
• 10 accumulates in the liver and kidneys
• Lead toxicity
• Muscle weakness, insomnia, lassitude, weight
  loss, colic, constipation, headache, memory loss,
  anemia, irritability, paralysis of extensor
  muscles of the wrist, dark line of discoloration
  on the gums, sterility in men, teratogen hazard
  for pregnant women

45
Lead Requirements

• Airborne lead action level 35 mg/m3
• Training about hazards and protection
• Showers and changing rooms
• Monitor levels in workplace air
• Provide engineering controls and PPE
• Medical surveillance program
• Regular blood level tests
• 29 CFR 1910.1025 and 1926.69

46
Cadmium

• Present in lead and zinc ores
• Used in alloys, electroplating, pigments,
  corrosion-resistant coatings, batteries,
  fungicides
• Inhalation to blood stream to liver and kidneys
  (damage to renal tubules)
• Biological half-life 20 years
• Acute exposure can be fatal
• Chronic exposure
• anemia, liver kidney damage, emphysema, heart
  damage, reproductive system damage, teratogen,
  carcinogen
• 29 CFR 1910.1027

47
Chromium

• Smelting, ore extraction, processing, alloy
  manufacturing
• Used in pigments, wood preservative, photographic
  chemicals, anti-corrosive additives in boilers
  and cooling systems
• Hexavalent (Cr6) is most hazardous, followed by
  Trivalent (Cr3)

48
Hexavalent Chromium (Cr6)

• Irritating and corrosive
• Inhalation of dust / metal fumes, mists during
  electroplating skin absorption
• Exposure symptoms
• coughing, headaches, breathing pain, fever,
  weight loss, nose ulcers, perforation of nasal
  septum, chronic bronchitis, skin discoloration,
  erosion of teeth, increased risk of lung cancer,
  liver and kidney damage
• 29 CFR 1910.1000

49
Organic Particles

• Inhalation of some organic particles can lead to
  lung impairments
• Reactive Airway Disease
• Tightening of the chest, wheezing, shortness of
  breath
• Byssinosis (cotton, linen, hemp, flax)
• Made worse with cigarette smoking
• Allergic alveolitis
• Inhalation of spores from fungi and molds,
  protein molecules
• Involves small terminal branches of bronchioles,
  just outside the alveoli
• Symptoms coughing, increased production of
  mucus, fever, fatigue, muscle aches
• Diagnosis can be confused or missed because of
  similarity to other illnesses such as pneumonia

50
(No Transcript)
51
Evaluating Lung Impairments

• Scarring and damage of lung tissue causes two
  distinct patterns of impairment of lung function
• Obstructive
• Restrictive
• Spirometry
• Lung function test
• See Figure 4-6

52
Obstructive Impairment of Lung Function

• Results from damage to small airways or
  bronchioles
• Decreased ability to exhale air
• Coal deposits can cause permanent dilation of
  small air passages, reducing volume of air that
  can be forced out
• Expiratory Volume volume of air that can be
  exhaled can be measured for evaluation

53
Restrictive Impairment of Lung Function

• Vital Capacity maximum volume of air that can
  be inhaled and then exhaled normally (see next
  slide)
• Restrictive impairment a reduction in this
  volume
• Physically demanding tasks become more difficult
• Caused by fibrotic lesions which reduce alveolar
  surface area

54
(No Transcript)
55
(No Transcript)
56
(No Transcript)
57
Oxygen-deficient Atmospheres

• Normal atmospheric oxygen 20.9
• Oxygen-deficient atmosphere (OSHA)
• lt 19.5
• Symptoms dizziness, loss of coordination, loss
  of consciousness, hypoxia, anoxia, death
• Hypoxia lack of oxygen to tissues
• Anoxia severe hypoxia leading to permanent
  damage
• Oxygen-enriched atmosphere
• gt 23
• Fire or explosion hazard

58
Oxygen-deficient Atmosphere

• An issue with OSHAs Confined Space Regulation
• Test prior to entry
• 29 CFR 1910.146
• Confined Space Permits
• Environments
• Tanks, tunnels, vats, bins, trenches
• Other hazards
• Oxidized metals inside tanks (uses available
  oxygen), decomposition of vegetation, inert
  gases, chemical asphyxiants, evaporative cleaning
  solvents, welding/cutting inside tanks

59
(No Transcript)
60
Chapter 4 Assignment

• Read Chapter 4
• HW4
• Critical Thinking Questions
• P. 97
• 1-6
• Due?