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INTRODUCTION TO OCCUPATIONAL HEALTH |
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Fumes |
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Fumes are formed when the material from a volatilized solid condenses in cool
air. The solid particles that are formed make up a fume that is extremely fine - usually
less than 1.0 micron in
diameter. In most cases, the hot vapor
reacts with the air to form an oxide. Gases and
vapors are not fumes, although the terms are often mistakenly used interchangeably.
Welding, metalizing, and other operations involving vapors from molten metals may produce
fumes; these may be harmful under certain conditions. Arc welding volatilizes metal vapor
that condenses - as the metal or its oxide - in the air around the arc. In addition, the
rod coating is partially volatilized. These fumes, because they are extremely small, are
readily inhaled. Other toxic fumes - such as those formed when welding structures that have been painted with lead-based paints, or when welding galvanized metal - can produce severe symptoms of toxicity rather rapidly in the absence of good ventilation or proper respiratory protection. |
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