Download Respirable Dust: Sec. 2

Control of Airborne
Respirable Dust Hazards:
A Training Program for
Underground Coal Miners
Penn State
The Penn State
Miner Training Program
University Park, PA 16802
March 31, 2003
Raja V. Ramani, Ph.D., P.E, C.M.S.P.
Mark C. Radomsky, Ph.D. MPA, C.M.S.P.
Joseph P. Flick, M.S., C.M.S.P.
CENTERS FOR DISEASE CONTROL
AND PREVENTION
NATIONAL INSTITUTE FOR
OCUPATIONAL SAFETY AND HEALTH
GENERIC MINERAL TECHNOLOGY
CENTER ON RESPIRABLE DUST
PENNSYLVANIA BUREAU
OF DEEP MINE SAFETY
RESPIRABLE DUST
TRAINING PROGRAM
Section 2
HUMAN RESPIRATORY
SYSTEM
Breathing Process
 Breathing is essential for living
 Humans at rest breathe about 10 to 12 times per
minute
 Air we breathe in mines
 must contain at least 19.5% Oxygen
 must not contain more than 0.5% Carbon Dioxide
 has limits on many other gases and dusts
found in the mines
Human Respiratory System
 Is a very complex system consisting of the
nose and mouth, windpipe, bronchial tubes,
lungs, bronchioles and alveoli. Alveoli are
surrounded by arteries and veins where gas
exchange takes place.
 Breathing substances that are harmful or in
amounts not ordinarily encountered in the
atmosphere can cause injuries to the system.
The main function of the lungs is to
provide oxygen to the body, and
eliminate carbon dioxide.
The average person breathes
in about eight liters of air
per minute
Liters
The average person uses
about 250 milliliters of oxygen
per minute
Milliliters
Breathing Basics
Air In
Air is breathed in through
the nose and/or mouth
 Air enters the windpipe (trachea)
 Air passes down the windpipe
(trachea) to the lungs.
Trachea
Breathing Basics
Bronchial Tubes
 The trachea divides into two
bronchial tubes, and a
bronchial tube enters each
lung
 The bronchial tube in each
lung divides and branches out
many times forming
progressively smaller
bronchial tubes called
bronchioles
Bronchioles
Breathing Basics
 At the end of the bronchioles are
small air sacs called alveoli
 There are millions of alveoli in the
human lungs
 The alveoli are surrounded by very
tiny arteries and veins
 This is where oxygen is given to the
bloodstream
Alveoli
Breathing Basics
 Oxygen is given to the blood
stream to be used, and carbon
dioxide enters the alveoli to be
exhaled out of the body
 The oxygen given to the blood
stream is carried to various
cells and organs.
 This process is known as
“Oxygen Transport”
Without Oxygen…
Without oxygen transport,
we would die in minutes
Oxygen
in
Carbon
Dioxide
out
Respiratory System Defensive
Mechanisms
 Nose, Mouth, Trachea, and Bronchial Tubes
all play a major role in evacuating inhaled
dust and preventing it from reaching the alveoli
 Special Cells in Alveoli (Macrophages)
engulf and try to digest the smallest particles
that enter this region
Respiratory System Defensive
Mechanisms
The respiratory system has an elaborate
defense network to try and allow only
clean air to reach the lungs
 The nose regulates (warms/cools) the temperature of
inhaled air
 The nose moisturizes inhaled air
 Small hairs in the nose trap particles for evacuation
Respiratory System Defensive
Mechanisms
The nose, trachea, and larger
bronchial tubes have cells with tiny
hair-like fibers called “Cilia” that
sweep in an upward direction to try
and evacuate inhaled particles
The nose, trachea, and larger
bronchial tubes are lined with a
mucus material which traps inhaled
particles. This mucus is moved by the cilia
to try and evacuate inhaled particles.
Cilia
Respiratory System Defensive
Mechanisms
 The process of the cilia and the mucus
working together to sweep and transport
inhaled particles upward is called the
“Mucociliary Escalator”
 It works much like a
human respiratory
conveyor belt
Dust
Dust is Ingested or Evacuated
Respiratory System Defensive
Mechanisms
 There are special cells in the alveoli
called “Macrophages” that engulf and
try to digest the very smallest
particles that have eluded all defense
networks
 Some substances, like coal and
silica, can damage the macrophages
Be kind to
your macrophages!
Don’t overload
them with dust!
Respiratory System Defensive
Mechanisms
 Only the very smallest particles can actually
enter the alveoli
 A small particle size is measured in microns. A
micron is expressed as (u m)
 The smallest particle that the human eye can
see is about 40 microns
 A human hair is about 50-70 microns thick
Respirable Versus Visible Particle
Size
<10
Respirable dust: <1 micron to approximately
microns 10 microns. Capable of being inhaled deep into the
respiratory tract and alveoli. Invisible to the human
eye.
Visible dust: approximately 40 microns.
40+
microns
The particles that
can cause illness
and disease
are so small
that you
can't see them!
Proceed to Section 3
Health Hazards of Coal Mine Dust