Types of Hazards

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Tab 2Respiratory System
Anatomy and Physiology
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1910.134(b)(10)Respiratory Protection

• Persons should not be assigned to tasks
  requiring use of respirators unless it has been
  determined that they are physically able to
  perform the work and use the equipment.

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Conditions which may limit respirator use

• any lung disease (e.g., emphysema, COPD,
  allergies, asthma)
• x-ray evidence of pneumoconiosis
• reduced pulmonary function
• heart disease
• cerebral blood vessel disease
• hypertension

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The Pulmonary System

• Exchange Oxygen and Carbon Dioxide
• Conduit and Oxygen Exchange Area

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Respiratory System

• function
• gas exchange between atmosphere blood
• parts
• upper respiratory system
• mouth, nose, pharynx, larynx
• lower respiratory system
• trachea, bronchi, bronchioles, lungs

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The Lungs

• very large surface area
  145 M2 in healthy male (or, about 40 times
  greater than surface area of our external skin)
• very thin membrane required at gas exchange area
  only 1/2 to 1
  micron thick in healthy persons
• micron?

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Micron

• one millionth of a meter
• about 1/ 1000th the size of a hair
• um

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The Nose

• Warms, cools air
• Humidifies air
• Filters particulates gt 10 microns (nose hairs
  and turbinate impaction)
• Reacts with water soluble gases
• Preferred entrance of air

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The Pharynx

• the chamber which collects incoming air and food
• passes air to trachea
• regulates air pressure and velocity
• filters particles (2 to 10 microns) through
  impaction
• reacts with water soluble gases

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Conducting Airways (Conduit)

• Trachea, Bronchi, Segmental Bronchi,
  Nonrespiratory Bronchioles
• Ciliated, Mucus Secreting
• Reduce in Diameter, Air Velocity the Further Down
  in System, Mucus Velocity
• Increase in Number of Generations, Surface Area

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The Trachea

• passage from pharynx to lungs
• the windpipe
• largest conduit to lungs
• filters particles 2 to 10 microns
• very sensitive (cough reflex)

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The Bronchi

• two subdivisions of the trachea
• one for each lung
• further subdivide into segmental bronchi
• filters particles 2 to 10 microns

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The Bronchioles

• smaller subdivisions of bronchi
• lower velocity settling
• flow less turbulent
• removes particles from 2 to 0.5 microns
• smooth muscle layer constricts

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The Alveoli (Air Exchange)

• respiratory bronchioles and alveolar ducts
• small air sacs
• covered with capillaries
• pulmonary artery
• pulmonary vein
• immunologic protection (macrophage)

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The Alveoli (Air Exchange)

• respiratory bronchioles and alveolar ducts
• small air sacs
• covered with capillaries
• immunologic protection (macrophage)

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Factors Determining Deposition

• size
• density
• shape (fiber, aspect ratio)
• solubility (water vs lipid)
• chemical composition (toxic vs inert)

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• The following slides are not for the class to
  see, but rather just instructor notes

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Types of Pulmonary Disease

• Obstructive- larger airways asthma, bronchitis,
  COPD, emphysema
• Restrictive- lung cannot expand fully or oxygen
  transfer inhibited hypersensitivity pneumonitis,
  asbestosis, silicosis, black lung, berylliosis

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Emphysema

• --occurs when adjacent walls in alveoli break
  through, causing a reduction in the number of air
  sacs
• --this decreases the total gas exchange surface
  that is available
• --over time, the lung becomes less elastic, and
  the outflow of air is obstructed

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Chronic bronchitis

• -- inhaled irritants cause excessive production
  of mucous in lower respiratory passages
• --they also cause inflammation fibrosis
  (hardening) of the skin surface (mucosa)
• --the result airway obstruction, poor
  ventilation of lungs, interference with the gas
  exchange process
• --also, bacteria thrive in the mucous, so
  pulmonary infections often occur

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Types of Defense

• nose hairs/ turbinates
• impaction / centrifugal / cyclonic
• cough reflex, sneeze reflex
• mucus blanket, ciliated cells
• bronchioconstriction
• settling, Brownian motion
• immune response

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Protective Measures

• Many of these defense mechanisms can
  deteriorate with age, or be compromised as a
  result of illness, tobacco smoking, or exposure
  to chemical irritants.
• So, choose control your exposures wisely!