X-Message-Number: 26148
Date: Sun, 8 May 2005 20:15:55 -0700 (PDT)
From: Doug Skrecky <>
Subject: Hydrogen Sulfide (H2S) information

[Hopefully safer means for inducing human hibernation will soon
be discovered. Below is some information sifted from the net.]

What is hydrogen sulfide (H2S)? Hydrogen Sulfide (H2S) is a
colorless gas that smells like rotten eggs (from the sulphur).
Often referred to as "sewer gas," hydrogen sulfide is highly
poisonous. Usually, the poisoning caused by hydrogen sulfide is
though inhalation and has a toxicity similar to cyanide. It is
found in petroleum and natural gas and is sometimes present in
ground water. Natural gas can contain up to 28% hydrogen sulfide
gas and may be considered an air pollutant when found near a
natural gas production area or refinery.  Low Levels of H2S The
odor or hydrogen sulfide gas can be perceived at levels as low as
10 ppb (parts per billion). At levels of 50-100 ppm (parts per
million), it may cause the human sense of smell to fail. Low
levels can cause eye irritation, dizziness, coughing, and headache.
High levels of H2S At high exposures (usually greater than 300 ppm),
H2S has the amazing effect of causing the nose to stop perceiving
its smell after a few inhalations, which may lead to the inhalation
of a toxic or fatal dose (which can occur at 600 ppm). At high
levels, hydrogen sulfide gas may paralyze the lungs, meaning that
the victim may then be unable to escape from the toxic gas without
assistance.  Deaths are not uncommon when people enter poorly
ventilated spaces such as deep wells, underground tanks or sewer
systems. Since H2S gas is heavier than air, its concentration is
highest near the bottom of enclosed spaces.

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