Date: Mon, 7 Sep 98 00:44:51 +0000

From: "Les. Gornall"

To:  "Biomass List Crest"

Subject: methane gas poisoning

I am looking for info re : methane gas poisoning.There is methane gas in the basement of my workplace.Myself and co-workers have all been ill.Could you send me any info that could help us get our employer to remedy this situation as they don't feel it is a risk to our health.

Tammy,

If this gas is of biogenic origin, from a landfill, old organic waste tip, or other organic source, I would be more worried about the H2S (Hydrogen Sulphide) concentration.

This normally appears with biogas, or biogenic methane sources.

The odour threshold is a few parts per billion in air and it smells of bad eggs. However, at higher concentrations - 1-3ppm you may not smell it as H2S numbs the olifactory nerves and effectively at these concentrations is odourless.

If the H2S is above 3ppm it may cause you health problems. At 10ppm the law limits the exposure to 8 hours per day - and from experience you will feel terrible after this level of exposure. At 15ppm the law limits your exposure to 15 minutes per day.

At a few hundred ppm -H2S in air you may pass out in less than an hour At a few thousands of ppm - H2S in air you may die on contact with the gas as the nerves around the heart and lungs are paralysed.

H2S when it enters the human body may split up to give a free HS (-) ion The HS (-) ion has the same destructive reaction in the body as CN = cyanide.

Just think of H2S as a gas which may have the same consequences as cyanide and you get the general picture.

H2S detectors are available on most sewage works sites and you might like to borrow one.

Best Regards

Les. Gornall Director Practically Green Environmental Services Solar House Magherafelt BT45 6HW Northern Ireland +44 1648 32615 Tel./Fax

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Updated 22 January 2004 by Paul Harris