Did a hazardous gas kill a utility worker in Cape Coral?
A chemistry professor at FGCU said hydrogen sulfide, which is common in sewers, could be the what caused the underground death of Anthony "Tony" Pimentel on May 25 in northwest Cape Coral.
Pimentel's family struggled with the nature of their dad’s death, given his three decades of experience doing what can be hazardous work in replacing water and sewer lines.
His death is being investigated by the Occupational Safety and Health Administration (OSHA).
Pimentel, 53, died shortly after noon, May 25, just north of Mariner High School. He lost consciousness while beneath a manhole and then most likely fell under water while doing construction work for Southwest Utility Systems in northwest Cape Coral, said Paula Rabe, who lived in the house adjacent to the manhole. Pimentel's employer declined to comment.
OSHA guidelines require two other workers for an authorized worker inside of an enclosed space: An attendant who is stationed outside, monitoring conditions within the space and preventing unauthorized entry and an entry supervisor, who oversees entry.
The Cape Coral Fire Department tested for oxygen and found the levels 20 percent at the surface and 13.3 percent an arm’s length into the hole. People require the oxygen level at 20 percent to survive.
The presence of hydrogen sulfide, a gas that occurs in sewers, could have been what knocked Pimentel unconscious, causing him to fall under the water, said Jose Barreto, professor of chemistry at FGCU.
“Hydrogen sulfide is naturally occurring in some human cells,” Barreto said. “It is part of a natural regulatory system that slows down heart rate and reduces blood pressure. That is another avenue for toxicity. If you encounter a concentrated cloud of the gas, your heart rate would slow down and blood pressure would drop. You might faint and thus be trapped, unable to leave.”
Barreto explained how hydrogen sulfide prevailed in the atmosphere during the early years of Earth.
- “The microorganisms that metabolize it once constituted all of the original life forms.
- “When algae appeared, it began to photosynthesize, converting water into oxygen, gradually filling the Earth’s atmosphere with oxygen. This gave rise to the ‘aerobes.’ Like many living things, humans are aerobes that require oxygen.
- “Anaerobes can only exist only in anoxic environments. Oxygen is a very deadly toxin to anaerobes. Septic tanks, marine and freshwater muds and sealed sewer lines are all examples of environments where anaerobes are abundant. Many of them produce and/or utilize hydrogen sulfide. They are killed by oxygen.
- “Conversely, if a person enters an anaerobic environment, they will begin to breathe hydrogen sulfide. They are inhaling a substance that is very toxic to an aerobe. The smell is described as 'disgusting' (an adaptation that signals danger) but, continued exposure to all strong smells ablates the human odor neurons.
- “The smell appears to 'go away' (even though the gas is still present). Further, hydrogen sulfide reacts with oxygen and depletes it in the ambient air of an enclosed space. This situation is dangerous to humans because the environment now contains a toxic gas and has insufficient oxygen.
- “If you stir a salt water mud flat, you might smell traces of hydrogen sulfide. You are mixing two, incompatible biological worlds that became separated eons ago. The organisms in the mud will encounter oxygen and die. The microorganisms in the water column will encounter hydrogen sulfide and die. These two environments are incompatible. Each organism is an 'alien' that will die in the other's world. Our planet contains two types of life forms that can never meet. A few centimeters of impermeable clay mud is sufficient to create a safe space for the anaerobes on our world.”
OHSA declined to comment on its investigation but spokesperson Eric Lucero shared construction protocol for “Permit Required Confined Spaces (PRCS) spaces such as manholes and sewers. They included:
- Identification and training of the component person
- Identifying all confined spaces at the worksite and determining which spaces are PRCS.
- Marking the PRCS to warn employees about the hazards
- Developing a Permit Required Confined Space Program for entering the spaces
- Training affected employees on PRCS entry requirements
- Develop and practice rescue procedures
Barreto said that had the manhole been ventilated with a fan, the oxygen in the atmosphere would have destroyed the hydrogen sulfide in a chemical reaction.
“Or, the worker could have worn a respirator,” Barreto said. “Devices with sensors for ‘low oxygen’ and detection of hydrogen sulfide are available. These could have warned the worker with alarms. A strong odor of ‘rotten eggs’ could have signaled to the worker that he should urgently leave that enclosed space! Even if the smell seemed to ‘disappear’ after a short time. It sounds like a preventable tragedy.”
How to help
Friends and family of the late Anthony "Tony" Pimentel have set up a gofundme.com account at gofundme.com/antonio-pimentel. They hope to provide financial assistance for Nelia Pimentel, Anthony’s high school sweetheart from their native Portugal and wife of 30 years.
“Tony was a great man and will be missed by everyone who knew him,” said Jovany Figueroa, a cousin. “Moments like these put life in perspective, make us care more about family, the loved ones around us, and not take any day for granted.”
Hydrogen sulfide
Some facts and standard procedures according to OSHA:
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).
Before Entering Areas with Possible Hydrogen Sulfide
The air needs to be tested for the presence and concentration of hydrogen sulfide by a qualified person using test equipment. This individual also determines if fire/explosion precautions are necessary.
If gas is present, the space should be ventilated.
If the gas cannot be removed, use appropriate respiratory protection and any other necessary personal protective equipment (PPE), rescue and communication equipment. Atmospheres containing high concentrations (greater than 100 ppm) are considered immediately dangerous to life and health (IDLH) and a selfcontained breathing apparatus (SCBA) is required.