What is sewer gas?
Sewer gas is a complex mixture of toxic and non-toxic gases that can be present at
varying levels depending upon the source. It is formed during the decay of household and industrial waste. Highly toxic
components of sewer gas include hydrogen sulfide and ammonia.
Sewer gas also contains methane, carbon dioxide, sulfur dioxide, and nitrous oxide. In addition,
chlorine bleach, industrial solvents, and gasoline are frequently present in municipal and privately-owned sewage treatment
How are people exposed to sewer gas?
Sewer gas can enter a home through a floor drain, from a leaking or blocked plumbing
roof vent, or (if the gases are in the soil adjacent to the house) through cracks in the foundation.
are the effects of exposure to sewer gas?
The principal risks and effects associated with exposure are:
Hydrogen sulfide poisoning. Exposure to low levels of hydrogen
sulfide causes irritation of the eyes and respiratory tract. Other symptoms include nervousness, dizziness, nausea, headache,
and drowsiness. This gas smells like rotten eggs, even at extremely low concentrations. Exposure to high concentrations
can interfere with the sense of smell, making this warning signal unreliable. At extremely high levels, hydrogen sulfide can
cause immediate loss of consciousness and death.
Asphyxiation. High concentrations of methane in enclosed areas can lead to suffocation as large amounts of methane
will decrease the amount of oxygen in the air. The effects of oxygen deficiency include headache, nausea, dizziness and unconsciousness.
At very low oxygen concentrations (<12%), unconsciousness and death may occur very quickly and without warning. Sewer
gas diffuses and mixes with indoor air, and will be most concentrated where it is entering the home. It can accumulate in
· Explosion and fire. Methane and hydrogen sulfide
are flammable and highly explosive.
How can I avoid being exposed to sewer gas?
Flush floor and sink drains with water to prevent the traps in pipes to the sewer from drying out.
check the roof plumbing vent for blockage from debris such as leaves or bird nests.
- Never enter a municipal sewer line, septic tank or any other large
storage tank without proper training and equipment.
I do if I suspect a problem?
Precision Locating can perform
a smoke or helium test to find the source, we have the equipment and experience necessary to locate any sewer gas
Symptoms of headache, nausea,
dizziness or drowsiness may indicate exposure to an odorless gas like methane or carbon monoxide, or to hydrogen sulfide,
which smells of rotten eggs. Persons experiencing severe symptoms should seek immediate medical care.
If you suspect that high concentrations of sewer gas have accumulated in an enclosed
space, you should evacuate the area and contact the fire department for assistance. Avoid creating an ignition source
such a spark from an electrical appliance, match, or cigarette lighter.