What is hydrogen sulfide?
Hydrogen sulfide is a naturally occurring, colorless, flammable gas. Hydrogen sulfide smells like rotten eggs when low levels of it are in the air. Because of this, hydrogen sulfide is also commonly called:
- Sewer gas
- Stink damp
- Manure gas
When hydrogen sulfide levels in the air are high, the air smells so sweet that it makes many people feel sick. At extremely high levels, you can temporarily lose your ability to smell the gas and become unaware that it is there. This condition, known as “olfactory fatigue,” happens for some people when they’re exposed to strong smells repeatedly or for an extended period of time.
Because hydrogen sulfide is heavier than air, it can build up in low-lying areas (like manure pits) and enclosed spaces (like silos or tunnels).
Where does hydrogen sulfide come from in the environment?
In the environment, hydrogen sulfide is produced from the bacterial breakdown or decomposition of dead plants and animals, especially when there is a lack of oxygen. In the environment, hydrogen sulfide is found many places, including:
- Unrefined natural gas and petroleum
- Volcanic gases
- Sulfur deposits
- Hot springs
- Swamps
- Beaches with large amounts of decaying seaweed and mudflats with trapped organic material (like dead plankton or fragments of shells) below the sediment
- Human and animal feces
Hydrogen sulfide is used by people to make other Sulphur chemical compounds, which are used in many fertilizers, car tires, medications, and preservatives. Hydrogen sulfide can also be a byproduct of other industrial activities and manufacturing, including:
- Pulp and paper mills
- Rayon fabric manufacturing
- Food processing
- Tanneries and fur processing
- Oil and natural gas refineries
How am I exposed to hydrogen sulfide?
Nearly all hydrogen sulfide exposure is from breathing air contaminated with hydrogen sulfide. Places where you can be exposed to hydrogen sulfide include industrial sites like pulp and paper mills, shorelines and beaches, visiting natural hot springs, and in rare cases, drinking water.
- Industrial sites
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Working in industries that make or produce hydrogen sulfide as a byproduct, or living near them, increases your chance of exposure to higher levels of Hydrogen Sulfide. This includes working at or living near:
- Pulp and paper mills
- Petroleum and natural gas drilling and refining sites
- Wastewater treatment
- Rayon textile manufacturing
- Tanneries
- Landfills
- Farms with manure storage pits
- Shorelines, beaches, and hot springs
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Working on or living near shorelines with significant amounts of decaying organic material, like seaweed, can increase your exposure to hydrogen sulfide. Mudflats with lots of buried organic material in the sediment can also produce low levels of hydrogen sulfide.
Additionally, soaking in hot springs exposes you to low levels of hydrogen sulfide.
- Drinking water
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Hydrogen sulfide can dissolve in water. It can be found in geothermal springs and some swamps. Although rare in Washington, municipal (public) drinking water or private well water can contain hydrogen sulfide. The most common sources of hydrogen sulfide in drinking water are iron and sulfur-reducing bacteria.
What are the health effects of hydrogen sulfide?
Most environmental releases of hydrogen sulfide (like shorelines, bogs, and volcanoes) are at levels too low to impact your health. Exposure to hydrogen sulfide at the levels listed below, however, could cause some health effects. Most health effects of hydrogen sulfide are short-term, and resolve when you move away from the exposure source.
Low levels (air smells like rotten eggs)
- Eye, nose, throat, and respiratory system irritation
- People with asthma may have a harder time breathing
Moderate levels (air smells sweet enough to make you feel sick)
- Severe eye and respiratory system irritation
- Headache
- Dizziness
- Nausea
- Vomiting
High levels (no smell in air)
Brief exposures to high levels of hydrogen sulfide can cause:
- Loss of consciousness
- Coma
- Death
In most cases, a person who is exposed to hydrogen sulfide will make a full recovery within hours to a few weeks. How your body responds to exposure to hydrogen sulfide depends on how long you were exposed, how much hydrogen sulfide you were exposed to, and how sensitive you are.
In some people, there have been permanent or long-term effects such as headaches, poor attention span, poor memory, and poor coordination. Long-term, low-level exposure to hydrogen sulfide may result in fatigue, loss of appetite, headaches, irritability, poor memory, and dizziness.
What should I do if I’m concerned that I was exposed to hydrogen sulfide?
Talk to medical provider if you’re concerned you were exposed to unsafe levels of hydrogen sulfide, or if you’re experiencing potential health effects.
Water
- Public Water System Customers
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If the water from your tap smells like rotten eggs or sickeningly sweet, contact your water system. Your water system’s contact information is on your water bill. You can also look up your water system online.
- Private Well Owners
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- If your tap water smells like rotten eggs or sickeningly sweet, contact the company or person who services your well. They may be able to help you identify the source of the hydrogen sulfide and fix it.
- Consider installing a water filter that removes hydrogen sulfide.
- Check with your local health department about any local regulations or rules about hydrogen sulfide in private wells.
Air
- Move away from where the air smells like rotten eggs or sickeningly sweet.
- If indoors, open a window to help ventilate the space.
- For industrial jobs, follow your employer’s safety plan.
- If you are concerned, talk to your local clean air agency. They can help you file an air quality complaint.