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Introduction
Local exhaust ventilation is the primary method used to control
inhalation exposures to hazardous substances. The system consists
of a hood, duct work, and an exhaust ventilation fan. In addition,
some systems are equipped with air cleaning devices such as HEPA
filters or carbon adsorbers. Types of local exhaust ventilation
system include fume hoods, vented enclosures for storing large equipment
or highly toxic chemicals, and flexible ducts or drops for capturing
contaminants near the point of release.
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Types
There are several types of fume hoods at MIT: laboratory fume hoods,
exhausted laminar flow hoods, biological safety cabinets, and perchloric
acid hoods. The laboratory fume hood is the most common local exhaust
ventilation system at MIT. When properly operated and correctly
used, a laboratory fume hood can control gases, dusts, mists, and
vapors released by volatile liquids. In addition, a laboratory fume
hood or other suitable containment device protects against inhalation
exposure to particularly harzardous substances-substances with carcinogenic,
mutagenic, reproductive, or high acute toxicity. Therefore, a laboratory
fume hood must be used when working with all hazardous substances.
The Material Safety Data Sheets (MSDS)
will help you identify hazardous substances.
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Warnings
Do not use a fume hood for storing large equipment unless the hood
is dedicated to this use. Large obstructions change fume hood airflow
patterns and may render the hood unsafe for other uses. It is generally
more effective to install a specifically designed enclosure for
large equipment so that the hood can be used for its intended purpose.
The Industrial Hygiene Program (IHP) can help design enclosures
for your special equipment.
Also, do not make any modification to the local exhaust ventilation
system without getting an approval from IHP first. Any changes made
to the system may result in unsafe conditions.
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The Industrial Hygiene Program
Room N52-496
77 Mass. Ave
Cambridge MA 02139-4307
452-3477
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