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Why Exposure to Hydrogen Sulfide Can Be Deadly

Odessa, TX – On the evening of October 26, 2019, a worker named Jacob Dean got an automated call to check on a pump house owned by Aghorn Operating, Inc. When he didn’t come home as expected and her attempts to reach him failed, his wife got their two children, aged 6 and 9, into the car and drove to the pump house. Natalee Dean parked at the site and got out of the vehicle to find her husband.

Neither Jacob nor Natalee lived to see another day. The young parents died from exposure to hydrogen sulfide. The gas was leaking from the pump house without warning because all eight of the hydrogen sulfide monitors at the site were not working properly.

Aghorn Operating and other defendants were subsequently indicted by a grand jury on nine counts, including Clean Air Act and Safe Drinking Water Act violations, making false statements to the Texas Railroad Commission, and violations of the Occupational Safety and Health Act. The Dean family also filed suit against Aghorn and others for their role in the loss of Jacob and Natalee.

This is just one example of the tragedy that can unfold as a result of hydrogen sulfide exposure. There are, unfortunately, many others. Understanding what hydrogen sulfide is, where exposure can occur, and who is responsible for protecting our workers and communities is a step in the right direction.

What Is Hydrogen Sulfide?

Hydrogen sulfide (H₂S) is a colorless, highly toxic gas that has the distinct smell of rotten eggs. The rotten egg odor can be quite strong at first, but continued exposure will deaden one’s sense of smell. Exposure to high quantities of hydrogen sulfide can eliminate one’s sense of smell immediately, making people completely unaware of its presence until it is too late.

Flammable and corrosive in high concentrations, hydrogen sulfide is used in several industries. It is a byproduct of industrial processes like mining, oil refining, and rayon manufacturing. It is used in pulp and paper processing and in the petroleum, rubber, and oil and gas industries. Hydrogen sulfide occurs naturally in wells, sewers, oil wells, and manure pits. It is also known as swamp gas, sewer gas, sink damp, and sour damp.

The Effects of Hydrogen Sulfide Exposure

Exposure to any amount of hydrogen sulfide can be harmful. In low concentrations, hydrogen sulfide can irritate the eyes, throat, and nose. Moderate concentrations can cause headaches, nausea, vomiting, coughing, and difficulty breathing. Just a few breaths of air containing high concentrations of hydrogen sulfide gas can cause convulsions, coma, and death.

Exactly how much hydrogen sulfide does it take to cause injury or death? The Occupational Safety and Health Administration (OSHA) offers helpful information on hydrogen sulfide exposure levels.

The following is a breakdown of hydrogen sulfide levels and the consequences of exposure:

  • .00011 to .00033 parts per million (ppm) is the amount of hydrogen sulfide typically occurring in the environment, or “typical background concentrations.”
  • At .01 to 1.5 ppm, the rotten egg smell associated with hydrogen sulfide may first become noticeable. At 3 to 5 ppm, the smell will be more pronounced and offensive.
  • Prolonged exposure to 2 to 5 ppm may cause nausea, headache, watery eyes, and sleep loss.
  • 20 ppm can cause memory problems, dizziness, headache, appetite loss, and fatigue.
  • 50 to 100 ppm can cause appetite loss and digestive upset. After one hour, respiratory tract irritation and conjunctivitis (pink eye) can occur.
  • Exposure to 100 ppm for 2-15 minutes can cause loss of smell, eye irritation, and coughing. After 15-30 minutes, drowsiness and breathing changes may set in. Symptoms may increase in severity as time goes on; after 48 hours, death may be imminent.
  • 100 to 150 ppm of hydrogen sulfide will cause loss of smell.
  • At 200 to 300 ppm, serious conjunctivitis and respiratory tract irritation may occur after 1 hour. Prolonged exposure at this level may cause fluid in the lungs (pulmonary edema).
  • Exposure at 500 to 700 ppm can cause a person to collapse within 5 minutes. The eyes will be seriously damaged within 30 minutes, and death may occur after about 30 to 60 minutes.
  • 700 to 1000 ppm can cause collapse and unconsciousness within just 1 or 2 breaths. Breathing will then stop, and death may occur within minutes.
  • Hydrogen sulfide exposure at 1000 to 2000 ppm will cause almost immediate death.

The recommended workplace exposure limit, per NIOSH, is 10 ppm (with a 10-minute ceiling). OSHA’s permissible exposure limit is 10 ppm for 8 hours for construction and shipyard workers and 20 ppm for general industry workers.

Does Hydrogen Sulfide Exposure Have Long-Term Effects?

For some people, hydrogen sulfide exposure will have long-term effects. If they lost consciousness as a result of breathing in high concentrations of hydrogen sulfide gas, they may experience ongoing headaches, memory problems, and issues with motor function after waking. Poor attention span is another potential consequence of hydrogen sulfide exposure. Cardiovascular problems have also been reported. These long-term effects, however, seem to vary from person to person.

Identifying Hydrogen Sulfide: How Is It Detected?

While hydrogen sulfide is most easily detected by its rotten egg odor, this is not a viable means of monitoring its presence. As already mentioned, exposure will lead to loss of smell, and if levels are high enough, this can be almost immediate. Facilities where hydrogen sulfide may be present should be equipped with working monitors that will identify unsafe levels and send an immediate alert. Employers should provide workers with wearable gas sensors to detect hydrogen sulfide. These monitors must be sturdy in construction to withstand the harsh environments in which they are used.

When monitors are not present or do not work, or when employees are not provided with appropriate wearable gas sensors, hydrogen sulfide can cause serious injury or death. That’s what happened to Jacob and Natalee Dean, and that’s what will continue to happen if companies do not take appropriate measures to put safety first.

Workplace Exposure to Hydrogen Sulfide

Hydrogen sulfide exposure is most likely in industrial workplaces.

According to the National Institute for Occupational Safety and Health (NIOSH), the following workers are at the highest risk of hydrogen sulfide exposure:

  • Oil refinery workers
  • Workers involved in natural gas extraction
  • Workers at rayon manufacturing plants
  • Wastewater treatment facility workers
  • Landfill workers
  • Agricultural workers on farms with manure storage pits
  • Sanitation workers who maintain or clean sewers and septic tanks

When hydrogen sulfide exposure is a possibility, employers must take the necessary steps to protect workers. This includes protecting them from chemical leaks, fires, and explosions as well as environmental exposure at any levels above OSHA limits.

OSHA’s Hydrogen Sulfide Fact Sheet lists specific measures that must be taken to protect workers from exposure. For example, the air must be tested for hydrogen sulfide before a worker enters the area. If hydrogen sulfide is present, the area must be ventilated constantly so the gas is removed. If hydrogen sulfide gas can’t be removed with constant ventilation, the worker must be provided with the right equipment to safely enter. This may include respiratory gear and other personal protective equipment (PPE) as well as gear that facilitates communication and rescue, if necessary. Workers must also be monitored for signs of hydrogen sulfide overexposure.

When Communities Are Exposed to Hydrogen Sulfide

Industrial workers aren’t the only ones who may be exposed to hydrogen sulfide. According to the Agency for Toxic Substances and Disease Registry (ATSDR), people may be exposed by breathing contaminated air or drinking contaminated water. Those who live near wastewater treatment plants, landfills, farms with manure storage, or oil and gas drilling operations will be at a higher risk of exposure.

A Navajo Nation community north of Montezuma Creek, Utah, experienced a rude – and terrifying – awakening on the morning of August 10, 2021. According to an article in The Salt Lake Tribune, Parnell Thomas reported waking early in the morning to the distinct rotten egg smell of hydrogen sulfide gas. With more than two decades of experience working in oilfields, he knew something was very wrong. Parnell pulled himself out of bed and made his way upstairs, where his children and their friends were sleeping. He managed to get them out of bed and out of the house, but several of the kids were already throwing up by the time they got outside. They drove to a relative’s house to escape the gas. Several other residents in the area reported that they too were awakened by the smell.

According to Elk Petroleum, it was the failure of the company’s vapor recovery unit located just over a mile away that caused the hydrogen sulfide leak. An automated alarm went off and alerted Elk Petroleum employees of the incident, and the leak was reportedly repaired within three hours, but not before Parnell, his family, and an entire community were put in danger.

When hydrogen sulfide is released into the air, it may remain there for anywhere from 1 to 42 days. When it is released into the water, it usually evaporates quickly. In soil, it is consumed by bacteria and turns into sulfur. The primary risk of environmental exposure to hydrogen sulfide is through contaminated air.

Hydrogen Sulfide: An Unseen Killer

In Parnell’s case, he was able to get himself and his family to safety. Others aren’t so lucky, and hydrogen sulfide exposure can come from unexpected places. That is the tragic story of a mother and her 3-year-old daughter, who were discovered in their 2006 Porsche Cayenne on Florida’s Turnpike in June 2016. The vehicle was still running, and authorities first believed that carbon monoxide poisoning caused their deaths. A urine test, however, revealed that hydrogen sulfide was the culprit. It had reportedly leaked from the vehicle’s starter battery underneath the front passenger seat.

In January 2017, 3 utility workers lost their lives within seconds of one another as they entered a narrow space underneath a manhole cover. A firefighter went in to save them, and he nearly lost his life as well. He could not fit through the narrow space while wearing his air tank, so he removed it. Upon entering the space where the workers were located, he collapsed almost immediately and had to be rescued by another firefighter. Hydrogen sulfide and methane gas were to blame.

The companies that use and produce hydrogen sulfide have a responsibility to their workers, the environment, and everyone in the vicinity of their facilities to observe state and federal regulations regarding emissions, equipment maintenance, lockout and tagout procedures, personal protective equipment, and more. They must have measures in place to prevent hydrogen sulfide leaks and to protect workers in areas where the gas is present. When they fail in any way to uphold these responsibilities, innocent people pay the price.

Accountability for Hydrogen Sulfide Exposure

At Arnold & Itkin, we have a proven record of holding oil and gas companies, manufacturers, and plant operators accountable for failing to protect workers and communities. We represented dozens of workers who were injured in the June 2013 Williams Olefins plant explosion, as well as workers injured in the 2005 Texas City refinery explosion, one-third of the Deepwater Horizon crew, and countless others. In all, we have recovered more than $10 billion for individuals and families who have experienced the worst injuries and losses. We fight to expose the greed and wrongdoing that lead to these catastrophes, and we win. No matter what.

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