Public Lab Wiki documentation

Hydrogen Sulfide

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A draft page for collecting and organizing information, questions, and projects related to hydrogen sulfide, also known as H2S.

Hydrogen sulfide is a colorless, flammable, extremely hazardous gas with a “rotten egg” smell. It occurs naturally in crude petroleum and natural gas, and can be produced by the breakdown of organic matter and human/ animal wastes (e.g., sewage). It is heavier than air and can collect in low-lying and enclosed, poorly ventilated areas such as basements, manholes, sewer lines and underground telephone/electrical vaults. (via

Framing the problem

  • Where is this an issue?
  • Who's working on this already?
  • What information is missing, if any? How will it change the situation?
  • What are they key parameters:
    • What intensities & exposure times are harmful to humans or the environment?
    • Where and how can it be detected? by smell range?
    • How long does it take to detect?
    • How fast does it move/change, or how large an area does it affect?
    • What kind of detection? presence/absence? direction of flow? intensity or locating a spot source?
  • What should the output data look like? Graphs, logs, lights, images?
  • What are the data’s uses/outcomes? Legal? Avoidance? Remediation? Regulation?

Where is this an issue?

Here I've ( @warren ) collected some of the notes folks have posted on about where H2S has been a problem, under the tag #h2s-sites :

Post more on H2S sites - help build out this list by posting your own notes on H2S-affected sites

Detecting H2S

Wikipedia's article, which is pretty well referenced, shows that:

0.00047 ppm or 0.47 ppb is the odor threshold, the point at which 50% of a human panel can detect the presence of an odor without being able to identify it.

This seems to be well below what's cited as a risk to health, but OSHA warns not to use smell as a means to detect it (

Can be smelled at low levels, but with continuous lowlevel exposure or at higher concentrations you lose your ability to smell the gas even though it is still present. At high concentrations – your ability to smell the gas can be lost instantly. DO NOT depend on your sense of smell for indicating the continuing presence of this gas or for warning of hazardous concentrations.

Most info I've ( @warren ) compiled here shows 10+ parts per million as when health effects are of concern, but one cites a TWA (time weighted average) of 1ppm -- over 8 hours. See below in the health effects section.

Questions about detection

Some questions to begin with include:

  • What equipment is available today, and who has access to it? How much does it cost and what is its sensitivity/latency? How much does it weigh and how does it work (air grab sample, continuous flow, soil sample?)
  • Are there alternative means of detecting which are dramatically different/cheaper?
    • silver film tarnishes with exposure to H2S, some sources cite discolored copper coins in someone's pocket as a way to diagnose a high exposure

We're collecting questions about H2S detection - please add your own here:

Ask a question  or help answer future questions on this topic

Health effects

Health effects vary with how long, and at what level, you are exposed. Asthmatics may be at greater risk. Low concentrations – irritation of eyes, nose, throat, or respiratory system; effects can be delayed. Moderate concentrations – more severe eye and respiratory effects, headache, dizziness, nausea, coughing, vomiting and difficulty breathing. High concentrations – shock, convulsions, unable to breathe, coma, death; effects can be extremely rapid (within a few breaths).

(Exposure information from

Exposure limits from various sources, from an Airgas Materials Safety Data Sheet:

ACGIH TLV (United States, 3/2016).
 STEL: 5 ppm 15 minutes.
 TWA: 1 ppm 8 hours.
NIOSH REL (United States, 10/2013).
 CEIL: 15 mg/m³ 10 minutes.
 CEIL: 10 ppm 10 minutes.
OSHA PEL 1989 (United States, 3/1989).
 STEL: 21 mg/m³ 15 minutes.
 STEL: 15 ppm 15 minutes.
 TWA: 14 mg/m³ 8 hours.
 TWA: 10 ppm 8 hours.
OSHA PEL Z2 (United States, 2/2013).
 AMP: 50 ppm 10 minutes.
 CEIL: 20 ppm

Note that these show toxicity at levels close to the ability of the wearable electronic monitors (see above) can detect -- 10-15ppm; "STEL" means Short Term Exposure Limit, or an "acceptable average exposure over a short period of time."


Please ask questions to help us expand this set of resources:

Ask a question  or help answer future questions on this topic

Existing work on Public

A range of projects related to H2S have been developed here over the years; we're going to try to organize it better, but for now:

Title Author Updated Likes Comments
What are the relative rates of hydrogen sulfide oxidation in ambient air? @gretchengehrke over 2 years ago 3
Article on monitoring hydrogen sulfide with a copper pipe @warren over 2 years ago 0
Toward calibrating H2S sensors. @JSummers about 5 years ago 1
Sensing Hydrogen Sulfide from CAFO Emissions in Poweshiek County, Iowa @sophie over 5 years ago 5
H2S Photopaper Processing notes @ewilder over 5 years ago 1
Hydrogen Sulfide Photopaper Sensing Tool - Development Notes @ewilder over 5 years ago 2
Quantifying Airborne Hydrogen Sulfide @JSummers almost 6 years ago 5
H2S photopaper test asasembly @Clarke_Brian over 6 years ago 1
Alternate Design for H2S Cannister @deepwinter almost 7 years ago 2
Interest in Hidrogen Sulfide Sensing @fernandolunav over 7 years ago 3
Putting together H2S Test Kit @megan over 7 years ago 1
First Experiment Analyzed @megan over 7 years ago 2
Easy ways to make precise maps @megan over 7 years ago 0
Identifying Wells in Field and Experiment Design @megan over 7 years ago 0
Choosing Test Sites in Aztec, NM @megan over 7 years ago 0
Gas, some Hydrogen Sulfide escaping from collapsing salt dome @eustatic over 7 years ago 0
monitoring industrial H2S sources in new orleans area @eustatic over 7 years ago 1
Field test #2: H2S strip placement in Bayou Sauvage NWR, Orleans Parish, LA @Shannon over 7 years ago 1
H2S strips batch 2: New Mexico @sara over 7 years ago 0
Safety Precautions for H2S Research @sara over 7 years ago 4
Bayou Sauvage Results 1: problems in labeling test strips @sara over 7 years ago 4
Bayou Savage Results 2: degree of canister openness @sara over 7 years ago 1
Bayou Sauvage Results 2: reflections on fixing process @sara over 7 years ago 2
H2S strip batch 1 for testing made 4/26 @sara over 7 years ago 3
Excellent Geoscience Fieldtest of Photostrip H2S Detection @sara over 7 years ago 0
Map of EPA National Priorities List sites with H2S issues @sara over 7 years ago 0
Map of New Mexico Natural Gas Wells in New Mexico and levels of Hydrogen Sulfide @sara over 7 years ago 0
Planning for Public Lab H2S screen Experiments-Equipment @sara over 7 years ago 0
Materials for Copper Pipe work @sara over 7 years ago 2
FOOLING OR REDUCING THE QUANTITY OF H2S (hydrogen sulfide) IN WELL TESTS. @sara almost 8 years ago 0
Possible sensor for field calibration of photo test strips @megan almost 8 years ago 0
H2S Experimental Set: Draft 1 @sara almost 8 years ago 0
Planning for Public Lab H2S screen Experiments @sara almost 8 years ago 0
Description: Horwell et. al. 2004 Experimental Set for Testing Photopaper test strips @sara almost 8 years ago 0
Procedure for Fixing H2S photographic paper strips @sara almost 8 years ago 0
Making Glycerol Solution for H2S film Assay @sara almost 8 years ago 0
Bibliography for Hydrogen Sulfide Research @sara almost 8 years ago 1
Hydrogen Sulfide Testing-glove bag @sara almost 8 years ago 4
H2S film strip test #2 @Shannon almost 8 years ago 2
Prototype for Filmbased Hydrogen Sulfide Testing strips @sara about 8 years ago 3
EPA Reinstates Toxics Release Inventory Reporting Requirements For Hydrogen Sulfide @sara about 8 years ago 0
Controlled Testing with B&W Film Hydrogen Sulfide Detectors @jschaffr about 8 years ago 2
Hydrogen Sulfide Dosimeter @sara about 8 years ago 0
Hydrogen sulfide detection for fart detector @warren about 8 years ago 0
Arduino + Figaro hydrogen sulfide sensor @warren about 8 years ago 1
Hydrogen Sulfide tarnishing Silver @sara about 8 years ago 1
Conversion from µg/m3 to ppm hydrogen sulfide @sara about 8 years ago 2
Hydrogen Sulfide Information on the Gas @sara about 8 years ago 0
Notes on Global Community Monitor Report on Bucket samples from Gas Patch @sara over 8 years ago 0
Hydrogen Sulfide Monitoring In Gas Patch Background @sara over 8 years ago 0
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