due to small amount stretched over weeks or months. Sudden, large exposure results
in inflammation, swelling, and narrowing of the airway, and in some cases the lungs fill
up with a fluid-a condition known as pulmonary edema. Those that primarily affect the
lungs, such as phosgene, often cause few, if any, symptoms at the time of exposure.
The employees may continue at their jobs, unaware that they have inhaled a dangerous
gas. Only after several hours do headache, vomiting, coughing, and shortness of
breath appear. In severe cases, death may occur. Prolonged exposure to small
amounts of irritant gas may produce a persistent cough or repeated cold-type infections
as the only symptoms.
(3) Prevention and control. The best prevention of exposure to irritant
gases is to ensure that they are not present in the workers' environment. This is best
accomplished by good engineering design and maintenance of the equipment on the
job. If exposure to some irritant gas is unavoidable, then provisions should be made for
appropriate personal protective equipment. Appendix B lists those representative
control measures used to reduce or eliminate the hazard from irritant gases.
b. Narcotizing Gases. Narcotic substances can produce unconsciousness and
many of the same symptoms that are exhibited with asphyxiates. The distinguishing
feature of narcotics is the effect on the central nervous system, causing it to fail to do its
normal job. Anesthetics and narcotics exert their principal action by causing simple
anesthesia without serious systemic effects, unless the dose is massive. Depending on
the concentration present, the depth of anesthesia will range from mild symptoms to
complete loss of consciousness and death. In accidents involving very high
concentrations, death may be due to asphyxiation. Substances like ether, chloroform,
and other anesthetics that are very effective in producing anesthesia are selected when
the intent is to make someone unconscious. In the industrial environment, there are
many things that have a narcotic action. Examples of these are acetone, methyl
bromide, and carbon disulfide.
c. Toxic Gases.
(1) Ethylene oxide, a common toxic gas, is used for sterilizing surgical
supplies. The high chemical reactivity and the general exothermic nature of ethylene
oxide reactions present a number of stable conditions, but the vapor in concentrations
of 3 to l00 percent is highly flammable and subject to explosive decomposition. Ignition
and decomposition are initiated by many common sources of heat, and the pressure
rise is sufficiently rapid and extensive to cause violent rupture of containing equipment.
The hazards of health associated with the handling of ethylene oxide are those of
inhalation of the vapor and contact of the eyes and skin with the liquid or solutions even
as dilute as one percent. Ethylene oxide may be described as a central depressant, an
irritant, and a protoplasmic poison. Contact with even dilute solutions may cause
irritation and necrosis of the eyes and irritation, blistering, edema, and necrosis of the
skin. Excessive exposure to vapor may cause irritation of the eyes, respiratory tract,
lungs, and central depression. Nausea and vomiting are usually delayed and may be