MetFab - Welding Fume Handbook - Flipbook - Page 10
3 Gases
operations, when the operator is close to 3.1 Health effects
the source of nitrogen oxides.
The potential health effects from
Carbon monoxide and carbon dioxide
inhalation of shielding gases or
pollutant gases generated by the
Carbon monoxide and carbon dioxide
welding process are:
are formed by the combustion of
fuel gases. They are also produced
during MMA and FCAW by the action
of heat on compounds in the flux.
Carbon monoxide may be generated
in significant quantities during
MAG welding using shielding gases
containing carbon dioxide.
Levels of carbon monoxide and carbon
dioxide generated by welding and
allied processes do not usually present
a health risk. An exception could be the
use of a carbon-dioxide-based shielding
gas when working in confined spaces.
Organic vapours
Irritation of the respiratory tract
Inhalation of nitrogen oxides can be
serious and even fatal. People exposed
to nitrogen oxides may at first suffer
little or no discomfort, or symptoms
that can seem trivial, including a
dry irritating cough and tightness of
the chest. Within 24 hours, however,
they may develop serious pulmonary
oedema (waterlogging of the lungs).
Ozone at low concentration irritates
the throat and airways, and stings
the eyes. At higher concentrations it
can cause bronchitis, pneumonia and
lung damage, and at high enough
concentrations it can be fatal.
A complex mixture of organic vapours
can be produced during welding or
cutting of metals carrying paint or other Trichloroethylene, which may be
organic surface coatings, or solvent from present following metal degreasing,
degreasing operations.
breaks down at the high temperatures
Though these vapours can contain toxic created by welding. The initial products
are mainly hydrochloric acid and
material such as phosgene, in general
the concentrations are well below their dichloroacetyl chloride, both of which
irritate the eyes and respiratory tract
exposure limits.
to the extent that the welder is likely to
stop work before serious health damage
occurs. Later breakdown products of
trichloroethylene include phosgene,
which can cause fatal pulmonary
oedema with delayed onset.
Asphyxiation
Shielding gas mixtures are typically
argon-based containing varying
percentages of helium, carbon dioxide,
hydrogen or oxygen. Shielding gases
contain little or no oxygen, so under
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