Photo of a TIF 8800 combustible gas analyzer being used to check a kitchen sink drain for sewer gas leaks Hydrogen Sulfide Gas (H2S)
Odors in Buildings, overlooked sources
     

  • HYDROGEN SULFIDE GAS - CONTENTS: Hydrogen Sulfide Gas H2S Odors, causes, sources, & hazards in buildings. heck these often overlooked sources of hydrogen sulfide gas, sewer gas, or sewage or septic smells & rotten egg or sulphur like odors. Other causes of sewage odors, septic odors, sewer gas, rotten egg, or other indoor gas odors. How to track down the sources & causes of sewer gas smells. Sewer gas smell diagnosis - plumbing checklist. Septic gas smell diagnosis - septic system checklist
  • POST a QUESTION or READ FAQs about often overlooked causes of hydrogen sulfide gas smells or H2S or sewer gas or septic odors in buildings
  • REFERENCES

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Hydrogen sulfide (H2S) gas sources in buildings: don't overlook these possible sources of sewer gas smells or hydrogen sulfide gas odors: here are the causes, sources, & cures for often overlooked sources of sewer gas smells. This article series explains how to diagnose, find, and cure odors in buildings including septic or sewage or sewer gas smells or "gas odors" in buildings.

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Hydrogen Sulfide or Rotten Egg Smells: building sources, causes, dangers, advice

Leaky cast iron building drain proven by septic dye (C) D FriedmanWatch out: both HYDROGEN SULFIDE GAS discussed here and METHANE GAS HAZARDS (both of these are present in sewer gases) are potentially explosive. In addition, exposure to high levels of these gases can be harmful, even fatal, as we detail below.

Because sewer gas contains methane gas (CH4) there is a risk of an explosion hazard or even fatal asphyxiation. Sewer gases also probably contain hydrogen sulfide gas (H2S) In addition some writers opine that there are possible health hazards from sewer gas exposure, such as a bacterial infection of the sinuses (which can occur due to any sinus irritation). Hydrogen is extremely flammable (easily set fire or explodes).

Depending on the sewer gas source and other factors such as humidity and building and weather conditions, mold spores may also be present in sewer gases.

Article series contents:

Sources of Hydrogen sulfide (H2S) or Septic System or Sewer Gas Odors are listed in a complete table at SEPTIC / SEWER ODOR SOURCE TABLE. Here are some key places to look:

Other H2S Odors, sewer-gas-like odors or sulphur odors may be hydrogen sulfide (H2S) and may occur from these conditions which you may not have considered.

  • Inspect the building water heater: if the "sewer gas smell" is noticed particularly when hot water is being run at a sink, tub, or shower, have your plumber check for a bad water heater sacrificial anode.

    This rod is intended to slow corrosion in the water heater tank but when the anode deteriorates it can cause a "rotten egg" smell in the hot water supply which may be mistaken for sewer gas. We discuss the hot water tank sacrificial anode and dip tube in more detail
    at Check the Sacrificial Anode & Dip Tube of Your Water Heater Tank.

    Watch out: Hydrogen sulfide gas is potentially explosive, can catch fire, and if it is mixed with or originating from sewer gases, it may contain pathogens or be harmful to humans and other animals. But in addition, water heaters can be a source of this sulphur or rotten egg smell due to bacterial growth or anode deterioration as we just cited. Water heater manufacturers, including American Water Heater Co., advise,

    Hydrogen gas is produced in a hot water system served by this heater that has not been used for a long period of time (2 weeks or more). Hydrogen is extremely flammable. To reduce the risk of injury under these conditions, it is recommended that the hot water faucet be opened for several minutes at the kitchen sink before using any electrical appliance connected to the hot water system. When hydrogen is present, there will be an unusual sound such as air escaping through the pipe as the water begins to flow. There should be no smoking or open flame near the faucet at the time it is open. [5]

    More details about dangers of hydrogen sulfide gas exposure are
    at Hydrogen Sulfide Gas H2S Exposure and

    at HYDROGEN SULFIDE GAS DANGER
  • Check the building water supply: if the "sewer gas smell" is a "rotten egg smell" and if it is noticed particularly when hot or cold water are being run at a sink, tub, or shower, your water supply may contain excessive hydrogen sulphide or H2S.

    This is not likely to be the case if you are on a municipal or community water supply but could occur if your water is supplied by a private well. Have the water tested for sulphur and H2S. If this condition is confirmed, the H2S is not a health concern but remains an aesthetic one.

    It can be corrected by installation of a proper water treatment system such as a chlorine injection system, a potassium permanganate filtration system, or by other methods. More information about causes of and cures for hydrogen sulfide odors in water is at Identifying Odors in Drinking Water.
  • Chlorine solution preparation during well disinfection or for water treatment equipment disinfection involves steps that can produce hydrogen sulfide. Watch out for hydrogen sulfide (H2S) during the mixing procedure. If there is H2S in the water you will need to aerate the water to dissipate that gas before adding vinegar (or chlorine) to the water. - see CHLORINE SAFETY WARNING where we discuss both H2S and chlorine gas hazards. Well shocking & disinfection are discussed
    at WELL CHLORINATION & DISINFECTION
  • U.S. Army Field Manual FM-8-285-Noxious_Chemicals discusses Ammonia, Carbon Monoxide, Hydrogen Sulfide, Oxides of Nitrogen, Hazards caused by fire
  • Use of improper or excessive cleaning chemicals in the building, or perhaps excessive use of antibiotics (such as by a nursing home served by a septic tank and whose residents consume a lot of antibiotics) can kill off bacteria in the septic tank. This is an unusual condition unlikely to occur in a normal homeowner environment.
  • Drywall outgassing:
    see CHINESE DRYWALL HAZARDS & ODORS for an explanation.
  • Septic system, sewer system, & building drain defects are common sources of sewer gases and hydrogen sulfide odors in buildings - but not if everything is working properly. But a loose toilet, blocked plumbing vent, improperly-maintained aerobic septic system, or a failing septic drainfield can be a source of sewer gas odors observed both indoors and outside. See SULPHUR & SEWER GAS SMELL SOURCES
  • For help in tracking down sulphur or sewer odors to their source: also
    see SMELL PATCH TEST to FIND ODOR SOURCE

    and SULPHUR & SEWER GAS SMELL SOURCES

Hydrogen Sulfide Gas H2S Explosion Dangers

Watch out: both hydrogen sulfide gas and methane gas (both present in sewer gases) are potentially explosive. Hydrogen sulfide gas is heavier than air, poisonous, corrosive, flammable (will burn), and depending on its concentration in air, it can explode.

My older sister Linda and later my best friend David Hoff both led experiments in attempts to light ... well, politely put, human flatulence gases. Results were amazing. But in buildings an accumulation of hydrogen sulfide gas H2S is not funny, it is potentially catastrophic, or fatal should an explosion occur. In dangerous mixtures with air or if put into direct contact with nitric acid, H2S explodes. (Fletcher 1999)

Compound is heavier than air and may travel a considerable distance to source of ignition and flash back. Hydrogen sulfide forms explosive mixtures with air over a wide range. Also reacts explosively with bromine pentafluoride, chlorine trifluoride, nitrogen triiodide, nitrogen trichloride, oxygen difluoride, and phenyl diazonium chloride. When heated to decomposition,

Hydrogen sulfide emits highly toxic fumes of oxides of sulfur. Incompatible with many materials including strong oxidizers, metals, strong nitric acid, bromine pentafluoride, chlorine trifluoride, nitrogen triiodide, nitrogen trichloride, oxygen difluoride and phenyl diazonium chloride. Avoid physical damage to containers; sources of ignition; storage near nitric acid, strong oxidizing materials, and corrosive liquids or gases. (Chemcial Book, Hydrogen Sulfide CAS No. 7783-06-04)

Hydrogen Sulfide Gas H2S Exposure Dangers

The following information about hydrogen sulfide gas H2S hazards is adapted from information from U.S. Army Field Manual 8-285 Chapter 10, Noxious Chemicals:

10-4. Hydrogen Sulfide Gas Danger Information

Physical Properties of Hydrogen Sulfide Gas:

This colorless gas in low concentrations has the odor of rotten eggs. In high concentrations it may dull the sense of smell and be difficult to recognize.

Occurrence of hydrogen sulfide gas in military operations. This gas is produced during the decomposition of sulfur containing compounds in sewers, waste, coal bins or stacks, holds of ships, and waterfront excavations.

Occurrence of hydrogen sulfide gas in Military Operations as well as in civilian and residential conditions

Hydrogen sulfide gas is produced during the decomposition of sulfur containing compounds in sewers, waste, coal bins

Pathology of Hydrogen Sulfide Gas Exposure

In low concentrations (less than 0.15 mg per liter), hydrogen sulfide may produce inflammation of the eyes, nose, and throat if breathed for periods of 1/2 to 1 hour.

Watch out: higher concentrations of hydrogen sulfide (H2S) gas (0.75 mg per liter or greater) are rapidly fatal, presumably by combination of the hydrogen sulfide with the respiratory tissue pigments and the subsequent paralysis of the respiratory center.

Symptoms of Hydrogen Sulfide Gas Exposure

The symptoms depend upon the concentration of the gas. At the lowest concentrations, the effects are chiefly on the eyes; that is, conjunctivitis, swollen eyelids, itchiness, smarting, pain, photophobia, and blurring of vision. At higher concentrations, respiratory tract symptoms are more pronounced. Rhinitis, pharyngitis, laryngitis, and bronchitis may occur. Pulmonary edema may result. At very high concentrations, unconsciousness, convulsions, and cessation of respiration rapidly develop.

Details about H2S exposure effects & limits are at

Treatment for Hydrogen Sulfide Gas Exposure

Immediately remove the casualty from the contaminated atmosphere and administer assisted ventilation with oxygen, if possible. Treatment of pulmonary edema is the same as for that caused by CG (chap 5).

Reader Comment: Hydrogen Sulfide Gas H2S health hazards warning & citation of HUD Dictionary of Deficiency Definitions

Not a question just a comment.

HUD regulates how to keep those in living in subsidized housing from the dangers of sewer gas inhalation but the state of Georgia (Georgia Dept. of Community Affairs a HUD area housing administrator) does not follow that HUD mandate and that is why myself and my child have severe lung disease that is caused from our prolonged exposure to sewer gas within and about a Bremen, GA rental.

See page 305 Sewer Odor Detected (Air Quality) quoted below:

Deficiency:
You detect sewer odors that could pose a health risk if inhaled for prolonged periods.

- SB4Justice - 4/4/2013

Reply:

SB4Justice

Thanks I've posted your remark above so that I could include a link to the Hud Deficiencies Definitions document provided by U.S. HUD.

Also below in our references we include citations [3][4][5][6][7][8] describing the health hazards of breathing hydrogen sulfide gas H2S, and of course methane can be a more immediate hazard - that of explosion.

Details about Hydrogen Sulfide gas and advice about tracking down such odors are on this page in the article above.

Details about methane gas hazards are given separately at METHANE GAS, SEPTIC / SEWER.

Watch out: while H2S can be dangerous, readers should keep in mind that both H2S and more commonly methane gas (a significant component in sewer gas) is dangerously explosive and at sufficient concentrations can also be fatal. So both can be an immediate hazard, not just a health hazard.

The same HUD Deficiencies document you cite, back up on page 304 also warns:

Propane/Natural Gas/Methane Gas Detected (Air Quality)

Deficiency: You detect strong propane, natural gas, or methane gas odors that could:

  • pose a risk of explosion/fire
  • pose a health risk if inhaled
Mildew on Jasmine plant leaves indoors (C) Daniel Friedman

And from HUD Pass/Fail deficiencies p. 302 we have more general advice

Air Quality (Health and Safety)


Indoor/Outdoor spaces must be free from high levels of sewer gas, fuel gas, mold, mildew, or other harmful pollutants. Indoors must have adequate ventilation.

The following deficiencies can be noted:

Mold and/or Mildew Observed
Propane/Natural Gas/Methane Gas Detected
Sewer Odor Detected

Which is in error only that mildew is never found in buildings, only mold, unless the mildew is growing on a plant (my photo at left). Mildew is an obligate parasite that only grows on plants. Of course normal people don't know that and the word "mildew" is used by lay persons interchangeably (if incorrectly) with "mold". Details are at MILDEW in BUILDINGS ?

Thank you again SB4Justice for pointing out these dangers. Working together we're smarter. - Daniel F.

Question/Comment: Hydrogen Sulfide Gas H2S health hazards in sewer gases

Not a question just a comment.

HUD regulates how to keep those in living in subsidized housing from the dangers of sewer gas inhalation but the state of Georgia (Georgia Dept. of Community Affairs a HUD area housing administrator) does not follow that HUD mandate and that is why myself and my child have severe lung disease that is caused from our prolonged exposure to sewer gas within and about a Bremen, GA rental. See page 305 Sewer Odor Detected (Air Quality) quoted below:

Deficiency:
You detect sewer odors that could pose a health risk if inhaled for prolonged periods.

- SB4Justice - 4/4/2013

Reply:

SB4Justice

Thanks I've posted your remark above so that I could include a link to the Hud Deficiencies Definitions document provided by U.S. HUD.

Also below in our references we include citations [3][4][5][6][7][8] describing the heatlh hazards of breathing hydrogen sulfide gas H2S, and of course methane can be a more immediate hazard - that of explosion.

Details about Hydrogen Sulfide gas and advice about tracking down such odors are at ODOR SOURCES SEPTIC OR SEWER

Details about methane gas hazards are at METHANE GAS, SEPTIC / SEWER.

Watch out: while H2S can be dangerous, readers should keep in mind that both H2S and more commonly methand gas (a significant component in sewer gas) is dangerously explosive. So both can be an immediate hazard, not just a health hazard.

Details about hydrogen sulfide or H2S - that sulphur smell principal ingredient, are at HYDROGEN SULFIDE GAS

Thank you again SB4Justice for pointing out these dangers. Working together we're smarter. - Daniel F.

 

 

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