Overview of Hyperbaric Medical Considerations for Occupational Exposure to Compressed Gas Environments
Jobs involving compressed air work include professions like construction workers in tunnels, commercial divers, and people who monitor multi-person hyperbaric chambers. All of these jobs have something in common – they involve working under high pressure situations. Essentially, this means that the air around the workers is denser than normal. To keep things simple, we’ll refer to everyone in these professions as compressed air workers.
In the construction of tunnels, compressed air has an essential purpose. Workers use it to stop groundwater from entering the tunnel and to prevent harmful gases (like methane) from seeping in. The compressed air industry has changed a lot over time. Back in the 1800s, workers created tunnels and caissons (watertight structures used for construction) manually. This meant they had to handle high-pressure conditions themselves, which led to a condition known as the bends or decompression sickness. This sickness can cause pain in the hips and spine and was common among these workers.
Fast forward to today, and most of this type of work is performed by highly trained commercial divers. They perform tasks underwater using compressed air. Divers are now less prone to the bends or air gas embolism (a dangerous air bubble in the bloodstream) due to better training programs and updating safety guidelines on safe decompression. Sometimes, the job sites might have chambers that can provide high-pressure air (hyperbaric chambers) and medical teams ready on stand-by, depending on how deep the work is.
Rules for compressed air work can be found on the Occupational Safety and Health Administration (OSHA) website under standard number 1926.803-Compressed Air. There are a lot of measures taken to keep compressed air workers safe. Still, workers in tunnel construction could still experience symptoms of decompression sickness and other risks related to construction work.
Anatomy and Physiology of Hyperbaric Medical Considerations for Occupational Exposure to Compressed Gas Environments
Decompression sickness, also known as ‘the bends’, happens when a person undergoes a rapid decrease in pressure, like coming up too quickly after deep sea diving. This can cause harmless gas bubbles that normally dissolve in the blood to form in the veins and other body spaces. Sometimes, these bubbles can enter the arteries, which is a serious condition called arterial gas embolism.
The symptoms of decompression sickness can vary widely. You might feel pain in your muscles or joints, or feel tingly, numb, or have unusual skin changes. More severe issues such as difficulty walking, changes to your vision, altered mental state, troubles with speech, or even paralysis are rare, but can happen. This condition can also cause problems with balance and hearing, and in rare cases, lead to distress in heart and lung functions or cause stomach problems.
Having a hole in the heart, also known as a patent foramen ovale, can make the condition worse. This is because it allows the gas bubbles to cross from veins into arteries, which can temporarily affect your vision and thinking abilities.
Why do People Need Hyperbaric Medical Considerations for Occupational Exposure to Compressed Gas Environments
With the rise of city development and the need for more infrastructures, the importance of workers who operate under high pressure environments, often called compressed air workers, has become more apparent. Even with the invention of tools like tunnel-drilling machines, these workers are still key to construction projects, particularly when the work involves operating under extreme atmospheric pressures. They primarily work on building and maintaining underground passages which are essential for transport, utilities, and other necessary services, especially in busy urban areas where there’s limited space on the ground.
Compressed air workers have a big role in operating tunnel-drilling machines. They typically work at the front part of the machine where the actual drilling takes place under high pressure. To get to this area, they need to go through a process which involves entering a high-pressure chamber known as a hyperbaric chamber, a process known as hyperbaric intervention. At this point, the front part of the machine is filled with bentonite, a type of mud-like substance, to create stability and stop the air from escaping. These hyperbaric interventions are crucial for regular check-ups, maintenance, and also for sudden emergencies like gas leaks or machine breakdowns.
These compressed air workers use special techniques for underwater operations, such as “saturation diving” and “bounce diving”. Saturation diving is when divers stay submerged for a long time, which allows them to work continuously without having to go through the long process of pressurizing and depressurizing repeatedly. This method is hugely beneficial for jobs such as deep-sea exploration, offshore construction, and maintaining oil rigs, especially when the work is more than 100-300 meters underwater. On the other hand, bounce diving involves quick dives and coming back up to the surface, and is used for jobs that needs frequent resurfacing. This technique is handy in tunnel construction because the workers can quickly reach their work area and get their jobs done efficiently. The decision on whether to use saturation or bounce diving depends on different factors such as how deep the job is, how long the task would take, and what resources are available.
When a Person Should Avoid Hyperbaric Medical Considerations for Occupational Exposure to Compressed Gas Environments
Keeping in mind one’s health and safety while working in environments with compressed air, similar to the conditions experienced during commercial diving, is crucial. This involves a thorough review of your medical background, any medications being taken, and your mental readiness. The review will also check if any medications or treatments could potentially be harmful when exposed to a high-pressure underwater environment.
Doctors specializing in undersea and hyperbaric medicine (medicine relating to the pressure of gases) should conduct these check-ups, ideally certified by professional bodies like the Association of Diving Contractors International (ADCI) and the Dive Medical Advisory Committee (DMAC). These experts use specific procedures to ensure the safety of workers involved in compressed air work. They provide full lists of situations or illnesses which might prevent safe working under pressures on their websites.
With compressed air work, the conditions can change a lot, and workers might face difficulties like changes in environment, technical issues, or emergency situations. Before starting any work, each worker needs to ensure their physical health and mental readiness, along with having the necessary skills for the job. To start, they need a doctor’s approval that they are fit. Then, they need to ask themselves three crucial questions:
1. Is my physical health good enough to take the strain required for this work?
2. Am I mentally ready to effectively handle hard situations?
3. Do I have the necessary skills and expertise needed for these specific tasks?
In other words, every person working in this field should have a personalized evaluation, going beyond just their medical history and medicines, to identify any reasons why they may not be suited for working with compressed air.
Equipment used for Hyperbaric Medical Considerations for Occupational Exposure to Compressed Gas Environments
Modern machines for digging tunnels, called tunnel-boring machines, are used in different sizes and depths, which requires the involvement of workers specialized in managing compressed air to ensure the machines work properly. The type of equipment used depends on many factors like the type of soil (rock or sand), how deep the machine will dig, location of groundwater, and the chance of hitting dangerous substances like methane gas. Even though workers who manage compressed air no longer manually dig tunnels, they are responsible for checking and replacing tools that are worn out or ineffective, such as ‘rippers’ and ‘cutters’. This is done to make sure the tunnel-boring machine continues to work smoothly and safely.
Work under high pressure conditions, often done at depths similar to repeated diving, has very low risk when supervised by professional diving companies, especially for depths exceeding 2.5 bar (25 meters underwater). A medical facility able to handle high pressure conditions, called a hyperbaric chamber, is located near the digging site to provide immediate medical treatment for workers managing compressed air who may experience decompression sickness. Before taking part in high pressure work, these workers have to complete a checkup dive to assess how they physically and mentally respond to high atmospheric pressure and thus confirm they are capable for this kind of work.
In a type of diving called saturation diving, workers with specialization in managing compressed air live in a special chamber, called a habitat, when they are not working. This chamber is above the ground and the teams of these workers are compressed together into a chamber called the saturation chamber. They use this chamber as their base while they are working. In order to reach and return from the work site, which is usually located underwater near the face of the tunnel-boring machine, workers make use of a special vehicle known as a hyperbaric shuttle or transfer capsule. Upon arriving at the tunnel-boring machine, the shuttle is connected to its specialized high-pressure chamber through a universal collar, allowing workers to enter the working area via a man-lock. Work shifts tend last from 6 to 8 hours, and then workers return to the habitat via the shuttle to be replaced by the next team. This method of saturation only requires one compression at the start and one decompression at the end. It uses different gas mixtures to reduce the risk of breathing toxic gases.
Who is needed to perform Hyperbaric Medical Considerations for Occupational Exposure to Compressed Gas Environments?
People who work with compressed air in various industries, like commercial diving and tunnel construction, have unique challenges. Although they all work with heightened atmospheric pressure, their training and health requirements are different.
Commercial divers, for example, follow strict health conditions set by bodies like the Association of Diving Contractors International. They also learn about specific health concerns related to diving. On the other hand, those working in tunnel construction learn about their specific jobs, like working with tunnel-drilling machines or dealing with increased pressure (hyperbaric) situations. They also get health checks that match these job requirements.
Commercial dive companies have an important part to make sure workers dealing with increased pressure stay safe. These companies offer specialized staff who know about the ‘hyperbaric chambers’ (rooms with high pressure) used in such jobs and the support equipment necessary for hyperbaric situations. These specialized staff closely work with onsite medical teams to ensure that workers get essential training, follow right procedures for entering and leaving high-pressure environments, get health check-ups after their work and immediate medical help in emergencies. These medical teams include doctors who might have to provide immediate care inside the high-pressure environments, especially if there’s a serious injury.
It’s very important to follow safety rules set by bodies like the National Institute for Occupational Safety and Health and OSHA to keep workers healthy and safe. However, these safety rules might need to be updated or applied differently for each project to stay compliant.
Preparing for Hyperbaric Medical Considerations for Occupational Exposure to Compressed Gas Environments
Before working with any high-pressure environment, workers are given a thorough introduction. This includes details about their specific job on site, possible risks, and how to safely adjust their body to the high-pressure environment and then back to normal again. They also learn about any possible side effects from working under these conditions. This information is given in a class-like lecture before the worker’s health and fitness for work under these conditions are checked by a medical expert.
They are also reminded to strictly follow the given plan for working under high-pressure conditions. If they don’t, there could be legal problems and potential health risks.
Interestingly, these high-pressure work environments often need special permission in the United States. This is because the rules from the Occupational Safety and Health Administration (OSHA), which is responsible for worker safety, are out of date. The rules needing an update relate to the safety of workers in high-air pressure environments and the right procedures for adjusting to high and normal pressures. Although the benefits of certain methods for decompression, or adjusting back to normal pressures, have been known since the 1960s, these methods are not included in OSHA’s rules. Dr. Eric Kindwall has brought attention to this in the past, but OSHA has not yet updated their guidelines to reflect current knowledge and practices.
How is Hyperbaric Medical Considerations for Occupational Exposure to Compressed Gas Environments performed
Bounce diving is a common technique used in the tunneling industry for wet and dry diving, especially when they need to perform high-pressure activity, which we call hyperbaric interventions. Here’s how it works: several teams of workers rotate around the clock, diving deep quickly, working for a brief period, then taking a long time to resurface slowly.
When the work area is dry, the workers are placed into high-pressure areas in the front of the tunnel-digging machines using chambers built specifically for this purpose. The amount of time they spend at the front of the machine depends on factors like depth and time, along with what kind of decompression guide they use. If the work area is wet or underwater, the workers breathe oxygen while resurfacing, to reduce the risk of decompression sickness, especially when they work at great depths.
Before starting work, a diving plan is made to set down details like how fast to increase the pressure, how long they will work, and what kind of gases they will breathe when decompressing. Oxygen is generally the default choice because it is safer. After their shift, the workers decompress in the hyperbaric chamber under the watchful eyes of trained operators and medical teams.
Saturation diving is an alternative method, even though it costs more, as it improves efficiency and lowers the risk of decompression sickness. In this method, the divers stay at the work depth for up to 28 days, making it unnecessary to keep diving and resurfacing daily. They only need to go through one cycle of diving and resurfacing – at the start and end of the project. They often breathe a mix of helium and other gases to protect themselves from harmful effects of too much oxygen and nitrogen, making sure their health is not compromised.
To ensure safety in the risky construction environment, construction companies often hire dive medical technologists who handle the operation of the chamber and provide onsite medical support. However, having one person do both jobs can be risky. It’s safer to have a specialized onsite medical team which might include technologists, nurses, and doctors with experience and certification in diving and high-pressure health care. Although this may cost more, it provides greater assurance of safety and quality health care for the workers.
Possible Complications of Hyperbaric Medical Considerations for Occupational Exposure to Compressed Gas Environments
There is not enough specific research on people who often work in environments filled with compressed air, also known as compressed air workers, and the different side effects they can experience. Despite this, the harmful effects can come in different forms, from the actual construction work and the atmospheric conditions where these workers function. Factors to consider include the quality of air, potential harmful substances, and what happens when a person breathes compressed air and other types of gases. Side effects from the construction work can vary from minor cuts to severe injuries, including amputations, burns, ergonomic injuries (injuries related to the way we move), and multiple injuries from falls.
Compressed air workers can breathe in air that may contain harmful substances such as methane, other gases, and dust. This can lead to short-term and long-term problems with the respiratory system, the part of the body that helps us breathe.
Other harmful effects can come from the machinery, physical attributes, and drug-related categories, specifically during compression and decompression in a hyperbaric chamber (a pressurized chamber filled with oxygen that you breathe in).
When people descend or go under compression in a hyperbaric chamber, it is common to have issues in the eustachian tube (a tube that links the pharynx to the middle ear) and the middle ear due to increased pressure in the external ear canal. This leads to negative pressure in the middle ear space when ventilation through the eustachian tube is not functioning properly. Ear pain is another common symptom, which can usually be eased by stopping compression and allowing for equalization or going up slightly in the chamber. Less commonly, sinus barotrauma (injury caused by changes in pressure) can happen, which can cause discomfort in the sinus, facial pain, or bleeding in the nose. Another thing to note is that after dental procedures, there can be spaces that are affected by gas compression and expansion, which can cause significant discomfort in the tooth or mouth.
Exposure to a lot of nitrogen due to diving in deep waters can be compared to the effects of alcohol, affecting judgment and response times. This can hinder the performance of compressed air workers. When using a mix of gases, precautions should be taken, particularly with helium and its association with high-pressure nervous syndrome. Chronic exposure to dust can also lead to conditions such as asthma, pulmonary fibrosis (lung disease that happens when lung tissue becomes damaged and scarred), and decreased lung function.
As a delayed effect of working in compressed air conditions, one can develop dysbaric osteonecrosis, a condition where bone tissues die due to a poor blood supply. This condition commonly affects the hip joint, which can lead to a high risk of fractures and the need for joint replacement. This condition is more prevalent in males aged 30 to 50, and those who are at risk should be regularly checked for any changes to their health status.
What Else Should I Know About Hyperbaric Medical Considerations for Occupational Exposure to Compressed Gas Environments?
People who work with compressed air, such as divers or tunnel workers, have unique health risks, and it’s essential that they’re regularly checked by doctors to ensure they’re fit for their jobs. Some health risks include bone damage known as dysbaric osteonecrosis, lung injury from pressure changes called barotrauma, and lung disease from inhaling fine dust, known as silicosis. In addition, these workers also face environmental and gas-related risks, such as effects of nitrogen, oxygen, and pressure on the nervous system.
It’s important that doctors working with compressed air workers are familiar with these risks and how to manage them. Regular medical check-ups can help spot any health problems early, which is important for keeping workers healthy and safe in their challenging work environments. However, the type and quality of healthcare these workers receive can vary, with different doctors taking different approaches.
Currently, Occupational Safety and Health Administration (OSHA) guidelines state that doctors caring for compressed air workers need to have experience with people exposed to extreme atmospheric pressure. This means that doctors should receive specific training and qualifications, just like any other medical specialty. In particular, specially trained undersea and hyperbaric medicine doctors are ideal for this role, because they have deep understanding of the challenges these workers face. It’s also important to keep proper health records for these workers, especially because they often move around for work, to ensure they receive consistent care.
While in the past, focus was mainly on conditions such as myopia (short-sightedness), decompression sickness (a condition caused by too rapid ascent from a dive), and silica exposure in tunnel workers, it is clear that more health issues need to be monitored nowadays. But even though there’s a strong need for more studies into these risks, such research is limited, and often relies on workers reporting their own experiences. Overall, major changes are needed to improve healthcare conditions for compressed air workers.
