Dauphin Island Fire and Rescue
1020 Chaumont Ave - PO Box 1596
Dauphin Island, AL 36528

National Threat Advisory graphic: elevated

Dauphin Island Fire and Rescue

Operating Guideline:

Hydrogen Sulfide Emergencies



Purpose: The purpose of this OG is to act as a guide when confronted with emergencies involving Hydrogen Sulfide. This guide should be used in conjunction with information from the producer, MSDS, CHEMTREC, EMA and other resources.

Hydrogen Sulfide is a substance associated in our area with the production of natural gas. Leaks can come from platforms, plants or pipelines. DIFR could encounter patients either at the site of the exposure (the Island) or patients brought for medical care from the point of exposure.

Hydrogen sulfide is a highly toxic and flammable gas. Being heavier than air, it tends to accumulate at the bottom of poorly ventilated spaces.

If treating a patient of H2S exposure without risk of contamination, remove the patient to an area with fresh air, place on high flow oxygen and remove loose clothing. If the patient complains of irritation to the eyes, skin, etc, irrigate with copious amounts of water. Once decontaminated transport the patient to the nearest appropriate facility. The nearest appropriate facility can be determined by contacting an Online Medical Director or Poison Control (1-800-222-1222). Patients involved in a Haz Mat Incident should not be transported by helicopter due to possible secondary exposures to healthcare providers.

A Hydrogen Sulfide (H2S) emergency should be suspected if you as a responder or a citizen complain of foul odor of sulfur or rotten eggs. Keep in mind that the body’s ability to smell H2S is paralyzed once the concentration reaches 150-200 ppm. Gas detection should be used to confirm its presence.

If you suspect there is a HYDROGEN SULFIDE leak do the following:

  1. Put on your PPE and move to a safe area upwind. PPE for the warm or hot zone is a SCBA and bunker gear unless directed otherwise. Be aware of the need of extra air bottle, hydration and heat fatigue.
  2. Establish a command post and staging area. Integrate DIPD and other agencies into a Unified Command System as outlined in NIMS. Get a wind direction and speed from Dispatch/DIPD to aid is choosing a command post.
  3. Notify Dispatch the following “County Dispatch this is ______ Command, we have a possible Hydrogen Sulfide leak. Notify EMA and that we need a shelter in place order given and we are requesting air monitoring equipment to the command post. We also need a Haz Mat Team to the command post"
    1. EMA should activate the EAS (Sirens, emergency alerting system). Sirens can be sounded by EMA or DIPD.
    2. DIPD may restrict entry to the Island.
    3. After consulting with DIPD establish a staging area for arriving mutual aid agencies. Examples may include the DI Marina, Cedar Point Pier or the Alabama Port Fire Station. Communicate that information clearly to dispatch.
  4. You will need to give a cell phone number to EMA and do not be afraid to ask for any resource you need. EMA may send MFRD Haz Mat and or Shell/Exxon Mobil Representatives.
  5. When air monitoring is available it should be used to find the Hot Zone (10 ppm). A second monitor should be placed at the entry point of the Cold Zone (consistent <10ppm) and a third at the command post. See chart below for air monitoring guidelines. See attached for an example of monitor deployment.
  6. Follow the OG for Hazardous Material Emergencies to deny entry to the Hot/Warm exclusion areas and communication guidelines.
  7. Any buildings with >10 ppm should be ventilated while wearing PPE.
  8. Expect demands from the public by appointing a Public Information Officer to speak on behalf of the Unified Command. This may be a town official or a representative from EMA. Avoid making any statements to the public or media unless the statements are FACTS. Do not use the words “I think”.
  9. Stand by to assist EMA and our mutual aid partners until the incident has been mitigated.


Monitoring of H2S and its effects on the body:

Exposure to lower concentrations can result in eye irritation, a sore throat and cough, shortness of breath, and fluid in the lungs. These symptoms usually go away in a few weeks. Long-term, low-level exposure may result in fatigue, loss of appetite, headaches, irritability, poor memory, and dizziness. Chronic exposures to low level H2S (around 2ppm) has been implicated in increased miscarriage and reproductive health issues amongst Russian and Finnish wood pulp workers, but the reports hadn't (as of circa 1995) been replicated. Higher concentrations of 700-800 ppm tend to be fatal.

  • 0.0047 ppm is the recognition threshold, the concentration at which 50% of humans can detect the characteristic odor of hydrogen sulfide, normally described as resembling "a rotten egg".
  • 10-20 ppm is the borderline concentration for eye irritation.
  • 50-100 ppm leads to eye damage.
  • At 150-250 ppm the olfactory nerve is paralyzed after a few inhalations, and the sense of smell disappears, often together with awareness of danger.
  • 320-530 ppm leads to pulmonary edema with the possibility of death.
  • 530-1000 ppm causes strong stimulation of the central nervous system and rapid breathing, leading to loss of breathing;
    • 800 ppm is the lethal concentration for 50% of humans for 5 minutes exposure (LC50).
  • Concentrations over 1000 ppm cause immediate collapse with loss of breathing, even after inhalation of a single breath.

A practical test used in the oilfield industry to determine whether someone requires overnight observation for pulmonary edema is the knee test: if a worker that gets "gassed" loses his balance and at least one knee touches the ground, the dose was high enough to cause pulmonary edema.

Attached Documents

·        Emergency Response Guide (ERG) for Hydrogen Sulfide type releases.

·        ERG Isolation Tables

·        DI Weather Buoy Web Page







The mission of Dauphin Island Fire and Rescue is to identify and respond to the community and deliver an effective and efficient system of services which minimize risk of life, health, and property from fire, trauma, acute illness and hazardous conditions.

This site was last updated on 03/26/2008