Particulates

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Particulates

• IENG 431
• Industrial Hygiene
• Dr. Carter Kerk
• Industrial Engineering Department
• South Dakota School of Mines

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Assignment

• Read Plog, Chapter 8
• Do HW8 as posted on course website
• Due Wednesday, March 18

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Introduction

• Basic Concepts
• Particle Size Distributions
• Determining Acceptable Exposure
• Biological Reactions
• Sampling and Analysis
• Biological Monitoring

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Particulate Examples

• Lead in paint
• Asbestos in schools
• Radon in homes

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Basic concepts

• Particulate Matter (PM) defined as small (less
  than 100 µm) pieces of solid materials, liquid
  droplets, or microbiological organisms
• Particles smaller than 0.001 µm start to act like
  gases and are not considered here
• Range 0.001 to 100 µm
• PM is considered a hazard when suspended in air,
  forming an aerosol, which can be inhaled
• Ingestion and skin contact are concerns also

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Nuisance dusts

• Airborne PM with little to no toxicity
• PNOC Particulates (insoluble) Not Otherwise
  Classified (ACGIH)
• PNOR Particulates Not Otherwise Regulated (OSHA)

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Types of pm (See Table 8-a)

• Dusts
• General produced by mechanical action (e.g.,
  grinding)
• Fibers asbestos, ceramic, fiberglass
• Biological (not organisms) wood cotton dust,
  animal dander
• Radioactive radon, radioactive waste, uranium
• Mists
• Fumes
• Biological agents
• Smokes

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Types of pm (See Table 8-a)

• Dusts
• Mists
• General droplets of liquid, e.g., droplets from
  bubbling dip tanks, paint overspray
• Fog droplets caused by recondensation of vapor
• Fumes
• Formed by evaporation and rapid condensation of
  metal vapor into very small particles, e.g.,
  welding, arc or torch cutting, foundry work
• Biological agents
• Smokes

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Types of pm (See Table 8-a)

• Dusts
• Mists
• Fumes
• Biological agents
• Living and non-living agents that may be
  allergenic, toxigenic, or infectious, e.g.,
  bacteria, viruses, fungal spores, prions
• Smokes
• Products of incomplete combustion of organic
  material, e.g., diesel exhaust, human tissue
  during laser surgery, second-hand cigarette smoke

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Specific hazardous PM (see table 8-b)

• Thousands of organic and inorganic PM found
  occupationally
• The most common categories of agents
• Arsenic, Asbestos, Bacteria, Beryllium, Cadmium,
  Chromium, Cotton, Cobalt, Diesel exhaust,
  Isocyanates, Lead, Manganese, Mold/Fungal Spores,
  Nickel, Pesticides, Radon, Silica/Quartz, Sodium
  Hydroxide, Thallium, Thorium, Uranium, Wood dust,
  Zinc oxide
• See Table 8-B for typical industries
  occupations and a summary of health effects

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pneumoconiosis

• Many classic chronic respiratory tract diseases
  attributed to inhalation of PM are broadly
  defined as pneumoconiosis

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Particle deposition mechanisms

• If a particle is deposited in the lung, where it
  is deposited may determine if it will contribute
  to an illness
• Five primary mechanisms of particle depostion
• Inertial impaction
• Interception
• Sedimentation (settling)
• Electrostatic attraction
• Diffusion (Brownian movement)

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Critical factors in determining acceptable
exposure to PM by inhalation

• Chemical and biological composition
• Stability of their nuclei (radioactivity)
• Crystalline, structural, and isotopic forms
• Shape and size of the particles
• Dose concentration and exposure duration
• Pre-existing health or genetic status of workers
• Concurrent exposure to other toxic agents

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Chemical biological composition

• Look at the relative hazard or toxicity in the
  TLVs or PELs
• Example) Compare iron, beryllium, and lead

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Chemical biological composition

• Look at the relative hazard or toxicity in the
  TLVs or PELs
• Example) Compare iron, beryllium, and lead
• Appendix B TLVs
• Iron 5 mg/m3
• Lead 0.05 mg/m3
• Beryllium 0.002 mg/m3

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Chemical biological composition

• Look at the relative risk for critical effects on
  the body
• Example) Compare inhalation of Bacillus anthracis
  to Bacillus subtilis
• They are closely related bacteria
• B. anthracis can cause anthrax, a potentially
  fatal disease
• B. subtilis is relatively harmless to inhale

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Particle size

• 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

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Size selective particle sampling

• Analyze for the relevant dust sizes rather than
  total dust
• Analyze under the microscope and count the
  relevant sizes, or
• Mechanically separate the particles prior to
  collection
• Filters or cyclonic
• Asbestos Fibers
• Count fibers under the microscope
• Look for fibers that are gt5µm long and have
  aspect ratio of 51 (ratio of length to width)
• We will see more of sampling later in the course

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Biological reaction examples

• Acute irritation of upper and middle respiratory
  system
• Irritants can induce rapid shallow breathing,
  dyspnea (or SOB), and breathlessness
• Lung edema (swelling)
• Allergic sensitization resulting in alveolitis or
  asthma
• Fibrosis scarring of lung tissue
• Emphysema destruction of lung tissue
• Systemic toxicity
• Lymphatic toxicity insoluble particles moved to
  lymph system by microphages
• Oncogenesis initiation or promotion of cancer
• Infections e.g., tuberculosis, Legionella,
  Hanta virus

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Sampling and analysis

• We will address this later in the course

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Biological monitoring

• Sampling for the absorbed absorbed dose in humans
  in blood, urine, and expired air thru a medical
  surveillance program, often prescribed in OSHA
  regulations, especially in industries with known
  exposures
• Typical suspects arsenic, cadmium, chromium,
  cobalt, fluorides, lead, organophosphorous
• See Table 8-L

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Assignment

• Read Plog, Chapter 8
• Do HW8 as posted on course website
• Due Wednesday, March 18