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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

  • POST a QUESTION or COMMENT about often overlooked causes of hydrogen sulfide gas smells or H2S or sewer gas or septic odors in buildings

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 © D Friedman at InspectApedia.com Watch out: both HYDROGEN SULFIDE GAS discussed here

and METHANE & SEWER 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.

Sources of Hydrogen sulfide (H2S) or Septic System or Sewer Gas Odors at Buildings

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.

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

HYDROGEN SULFIDE EXPOSURE EFFECTS

HYDROGEN SULFIDE GAS EXPOSURE LIMITS

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 [PDF] 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:

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.

Note: For a helpful discussion of just what constitutes "adequate venitlation", see

 

 




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Reader Comments, Questions & Answers About The Article Above

Below you will find questions and answers previously posted on this page at its page bottom reader comment box.

Reader Q&A - also see RECOMMENDED ARTICLES & FAQs

On 2019-09-03 by (mod) - house that was inundated with sewer gas (H2S) for a period of about 4 months

Jared

Before prescribing a "cure" for the indoor odor AND before deciding if the house is safe to live-in, it would be best to

1. Identify the odor source - so that removal, cleaning, or sealing are effectively focused - See the ARTILE INDEX to find

SMELL PATCH TEST to FIND ODOR SOURCE - an easy way to do that

2. Have the property's electrical and mechanical systems inspected for corrosion that could make electrical wiring, controls, or HVAC equipment unsafe - as H2S may have caused harmful corrosion: put safety ahead even of odor mitigation

See this example of such damage:

CHINESE DRYWALL HAZARDS where other links will suggest further investigation and mitigation.

On 2019-09-02 by Jared Raymer

My Mother has a house that was inundated with sewer gas (H2S) for a period of about 4 months. There is still some kind of smell that is in the house years later. Do you know of any ways to treat this house to keep items in the house from off gassing? like seal the walls and repaint?

Is there any way to know that this house is safe to live in?

The house was aired out after the incident happed. There was a ozoneator also ran in the house for a long period of time.

There is proof that the H2S was there due to the copper wiring in the walls by the outlets turning black and silver. Any advice on this problem would be greatly appreciated. Thanks, Jared

On 2017-09-02 by (mod) What does hydrogen sulfide smell like

Rotten eggs

On 2017-09-02 by Pamela Pawlowski

What does hydrogen sulfide smell like

On 2017-08-27 by Eva

Smell of sewer gas or rotten egg,worst when using A/C. Some days,unbearable,some days very faint smell

On 2017-07-26 by (mod) -

Not sure what would be the connection, Ray, but to be very safe you could turn off that circuit on the theory that a wire or component may be overheating.

Then see if you can track down where the odor is strongest - that'd be diagnostic.

Odors of sewage or sulphur often are due to a drain backup or septic failure that might show up in wet weather.

On 2017-07-25 by ray scott

We had a bad rain during the night when we woke up several lights were flickering and power to bathroom went off.

An electrician was called and he found the copper wire in a light fixture to be not connected tight. He fixed the problem and the lights started working. several hours later returned home to have a strong rotten egg smell in several rooms of the house.

Don't know what caused this. Any comments on problem. Thanks

On 2017-03-27 by (mod) -

Thank you, SmithE. Assuming you're not kidding me, I'll add that we work hard to provide researched, unbiased data so I'm happy when a reader finds our information useful.

Daniel

On 2017-03-27 by Smithe438

Usually I do not read writeup on blogs, nevertheless I wish to say that this writeup extremely forced me to take a look at and do so! Your writing taste has been amazed me. Thanks, really wonderful post. ffefekefcbdfbdef


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HYDROGEN SULFIDE GAS at InspectApedia.com - online encyclopedia of building & environmental inspection, testing, diagnosis, repair, & problem prevention advice.


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INDEX to RELATED ARTICLES: ARTICLE INDEX to BUILDING ODOR DIAGNOSIS & CURE

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