YOUR ENVIRONMENTHydrogen Sulfide

If you notice a rotten egg smell, this is an emergency.

Smell inside your home: Evacuate your home and call 911 or the Enbridge Emergency number at 1-866-763-5427.

Smell outside your home: Call the Spills Action Centre of the Ministry of Environment at 416-325-3000 or 1-800-268-6060 (toll-free)

What is Hydrogen Sulfide?

Hydrogen sulfide (H2S) is a colourless gas that smells like rotten eggs. At high levels, hydrogen sulfide can be flammable and is dangerous to your health. 

The gas occurs naturally in some environments including abandoned water wells, oil and gas wells, sulfur springs, and swamps. It is also produced by the breakdown of organic matter and can be associated with animal farms, industrial plants, sewers, or sewage treatment plants. 

How Can You be Exposed to Hydrogen Sulfide?

Hydrogen sulfide is part of the natural environment. You can only be exposed to the gas when you come into direct contact with it by breathing it in, eating or drinking something contaminated with it, or when it touches your skin. Any hydrogen sulfide that your body has absorbed does not accumulate because it is quickly broken down by the liver and is excreted through urine. Hydrogen sulfide usually breaks down in the air. Therefore, exposure to the gas is only a concern if a person is close to an ongoing source in a confined area. 

How is Hydrogen Sulfide Detected?

People usually smell hydrogen sulfide even at very low concentrations in the air, ranging from 0.0005 to 0.3 parts per million (ppm). These levels in the air are not dangerous and will not cause negative health effects. However, you cannot rely on your nose to tell you how much hydrogen sulfide gas is present. Hydrogen sulfide can be detected using a special equipment, like a multigas detector.  

What are the Health Effects of Hydrogen Sulfide?

Exposure to low concentrations (10-100 ppm) of hydrogen sulfide may cause: 

  • Irritation to the eyes, nose, or throat 
  • Difficulty breathing for some people with asthma 
  • Headaches 
  • Poor memory 
  • Tiredness 
  • Balance problems 

            Brief exposures to high concentrations of hydrogen sulfide (greater than 500 ppm) can cause a loss of consciousness. In most cases, the person will likely regain consciousness without any other effects. However, in some people, there may be permanent or long-term effects such as headaches, poor attention span, poor memory, and poor motor function. In very high concentrations, hydrogen sulfide is deadly.  

            What if I Smell Hydrogen Sulfide in my Well Water?

            If hydrogen sulfide is present in a water well, it can make water have a sulfur taste and look aesthetically unpleasant. The odor may be more noticeable when you run hot water because the heat forces the gas into the air. This may cause the odor to be very strong when showering.  

            Water samples submitted to CK Public Health Clinic Services are only sampled for bacteria at the Public Health Lab. Chemical testing (hydrogen sulfide or other chemicals) can be done for a fee through a licensed private lab. If there is an ongoing issue with hydrogen sulfide in your water supply, there are a variety of water treatment devices that can remove it. Consult a licensed plumber or a water treatment company to determine what water treatment device will best suit your needs. 

            Emergency Preparedness

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