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. Rate This Message: http://www.cryonet.org/cgi-bin/rate.cgi?msg=26148