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hydrogen-sulfide

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 [OSHA.gov](https://www.osha.gov/Publications/hydrogen_sulfide.html)) **** ## 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 PublicLab.org about where H2S has been a problem, under the tag #h2s-sites : [notes:h2s-sites] <a class="btn btn-primary" href="/post?tags=h2s-sites">Post more on H2S sites</a> - _help build out this list by posting your own notes on H2S-affected sites_ **** ## Detecting H2S [Wikipedia's article](https://en.wikipedia.org/wiki/Hydrogen_sulfide), 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 ([OSHA.gov](https://www.osha.gov/Publications/hydrogen_sulfide.html)): > 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](#Health+effects). #### 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?) * on [Google Shopping](https://www.google.com/search?gcx=w&ix=c1&sourceid=chrome&ie=UTF-8&q=hydrogen+sulfide+monitor#gcx=w&ix=c1&q=hydrogen+sulfide+monitor&um=1&ie=UTF-8&tbo=u&tbm=shop&source=og&sa=N&hl=en&tab=wf&bav=on.2,or.r_gc.r_pw.&fp=4e466e80d018bd5a&biw=1274&bih=702) - as low as $109 for 10-15ppm levels * 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: [questions:h2s] **** ## 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 [OSHA.gov](https://www.osha.gov/Publications/hydrogen_sulfide.html)) Exposure limits from various sources, [from an Airgas Materials Safety Data Sheet](https://www.airgas.com/msds/001029.pdf): ``` 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](https://en.wikipedia.org/wiki/Short-term_exposure_limit), or an "acceptable average exposure over a short period of time." ### Questions Please ask questions to help us expand this set of resources: [questions:h2s] ### Existing work on Public Lab.org 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: [notes:h2s]

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