Ergonomics - Atlas Copco

Dust and oil
The influence of these two factors on the
operator depends very much on the pro-
cess itself. The dust particles and oil
mist of interest for a hygienic evaluation
are so small that they will remain air-
borne for a long time. If the ventilation
in the workroom is poor, high concentra-
tions may occur.
What is dust and oil mist?
Pollutants in the form of airborne particles
can occur in both solid and liquid form and
can vary in size. A large amount of particles
floating in a bearing medium is called dis-
persion. When the bearing medium is air,
the dispersion is known as aerosol.
A fixed aerosol contains solid particles
which, when larger than 0.5 µm (1 µm =
1/1000 mm = 0.00004 inches) are called dust,
and when smaller, smoke. Dust is normally
created by mechanical finishing of materials,
like grinding or sanding, while smoke is the
product of incomplete combustion.
An aerosol containing droplets of liquid
is called fog when the size of droplets ex-
ceeds approx. 0.5 µm and smoke when the
droplets are smaller. The droplets can be
formed when a liquid is dispersed during,
for instance, spray painting or lubrication
of pneumatic tools.
Respirable aerosol
The most dangerous particles in an aerosol
have a diameter between 0.1 µm and 5 µm.
Particles >5 µm are filtered off in the
nose. Smaller particles have the ability to
follow inhaled air into the deepest inner
cavities of the lungs, the alveoli, and remain
there, although some are exhaled again.
This dust is termed respirable.
Inert particles
It is in the alveoli that gas exchange takes
place. The body emits carbon dioxide and
takes up oxygen. Thus, it is extremely
important that the alveoli do not become
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