El gas respirable seguro es el salvavidas del buceador bajo el agua, y su contaminación puede poner en peligro la vida o provocar lesiones graves. Los contaminantes pueden proceder de diversas fuentes, por lo que es importante comprender cómo se produce la contaminación, cómo reconocer las señales de alerta y qué hacer si se sospecha que se ha producido una contaminación.
Cómo se produce la contaminación
El gas respirable se comprime en cilindros mediante un compresor. Aunque los sistemas de compresión varían, todos cuentan con una válvula de admisión que aspira aire ambiente antes de la compresión. Los compresores también disponen de sistemas de filtración que eliminan los contaminantes, pero los filtros se deterioran con el tiempo y es necesario sustituirlos.
Las empresas de llenado de confianza deben seguir procedimientos de llenado seguros, realizar pruebas periódicas de la calidad del aire y llevar a cabo un mantenimiento rutinario de los compresores. Sin embargo, los problemas de mantenimiento, las condiciones ambientales, los fallos en los equipos, los errores en los procedimientos y otros problemas imprevistos dan lugar a que puedan entrar contaminantes en las botellas de gas respirable.
Las posibles fuentes de contaminación provienen de impurezas presentes en el entorno, como los gases de escape de los motores, el dióxido de carbono o las partículas de polvo, o bien de subproductos del proceso de compresión, como el monóxido de carbono (CO) o los hidrocarburos procedentes de los lubricantes de los compresores.
Las fuentes de contaminación dependen, en parte, de la ubicación de la válvula de admisión del compresor. En el caso de las tomas de aire exteriores, entre las posibles fuentes se pueden incluir los gases de escape de los vehículos, el humo, la materia orgánica o los residuos, la suciedad y cualquier fuente de combustión. En el caso de las tomas de aire interiores, entre las posibles fuentes se pueden incluir los vapores de pintura, las reformas recientes, los productos de limpieza, los productos químicos almacenados, una ventilación deficiente u otros contaminantes presentes en el aire.
Contaminantes y síntomas
Los síntomas de la contaminación del gas respirable pueden ser poco específicos y parecerse a los de otras enfermedades o afecciones relacionadas con el buceo. Si sospechas que has estado expuesto a gas respirable contaminado, acude al médico y, siempre que sea posible, haz que analicen el gas.
| TABLA DE CONTAMINANTES Y SÍNTOMAS | |
|---|---|
| Monóxido de carbono (CO) | Dolor de cabeza, mareos, debilidad, náuseas, vómitos, dificultad para respirar, alteración del juicio, confusión, pérdida del conocimiento. |
| Carbon Dioxide (CO2) | Hyperventilation, dizziness, confusion, unconsciousness. |
| Volatile Hydrocarbons | Fatigue, headache, confusion, impaired judgement, numbness, cardiac arrhythmias, loss of consciousness. |
| Oil (Condensed) | Headache, nausea, impaired respiratory function. |
| Dust (Particles) | Impaired respiratory function. |
CO is particularly dangerous because it is odorless, colorless, and tasteless. Without a testing instrument, CO can be difficult to identify before symptoms occur. CO detection devices include disposable early-warning devices and dedicated analyzers. Other contaminants may give breathing gas a distinct smell or taste, but the absence of odor or taste does not rule out contamination.
How to Identify Gas Quality Issues
Conduct a Predive Gas Check
Conducting a predive gas check on every cylinder can provide an early warning sign of a potential problem. This check should include smelling and tasting the gas, testing for CO, and analyzing the oxygen content.
- Smell and Taste Check: If breathing gas has an unusual or unpleasant odor or taste, do not dive with it.
- CO Analysis: Some fill operations use continuous CO monitors, but using a personal portable CO analyzer is a valuable additional safety measure for individual divers.
- Oxygen Analysis: While oxygen is not a traditional contaminant, cylinder mislabeling and mixups can be potentially dangerous. Analyzing the oxygen content of every cylinder ensures divers know exactly what percentage of oxygen they are breathing and can plan their dives accordingly
Assess the Filling Environment
When visiting a new dive operation, take time to assess the environment and observe filling practices. Look around the fill station and the surrounding area for possible contamination sources. Compressor intake valve locations vary, and it is appropriate to ask where the intake valve is located and whether you may see it. After identifying the location, consider the following questions.
| If the Intake is Indoors | If the Intake is Outdoors |
|---|---|
| Is the area clean and organized? | Is the intake valve protected? |
| Is it well ventilated? | Is there organic debris near the intake? |
| Does the room have a noticeable smell? | What is the outdoor air quality like? |
| Are chemicals, fuels, paint, or cleaning products stored nearby? | Is the shop near any roads, factories, restaurants, or other pollution sources? |
| Has the building been renovated recently? | Is anyone smoking nearby? |
| Are staff cooking or cleaning while the compressor is running? | Are gas-powered boats, vehicles, generators, or compressors running nearby? |
The key to situational awareness is observation. Be aware of shop procedures. Do workers seem to follow a specific filling protocol? Does the shop have posted safety signage, operator credentials, and air-quality documentation available? Are divers reporting an odor or taste in their tanks, or experiencing symptoms after dives?
Observation can provide clues, but it is also appropriate to ask questions about the shop’s filling safety procedures and precautions.
Consider asking:
- What steps do you take to ensure breathing gas quality and compressor safety?
- How often do you test air quality?
- May I see your most recent air quality test certificate?
- How often is the compressor serviced?
- May I see your maintenance logs?
- Do you test for carbon monoxide (CO)?
Speak Up About Concerns
If you have concerns about a cylinder, notify shop personnel. Breathing gas concerns should be taken seriously. If concerns are dismissed, documentation is unavailable, or staff members are unwilling to discuss safety procedures, consider whether the operation meets your expectations for safe diving. Depending on the circumstances, unresolved concerns may warrant further discussion with shop management or another appropriate authority.
Asking questions and voicing concerns may feel uncomfortable in the moment, but speaking up can help protect both your safety and the safety of others. Early identification of breathing gas safety issues can help prevent incidents before they occur.
DAN offers gas analysis assistance. If you were involved in an incident possibly related to breathing contaminated gas and you have lawful control of the tank, preserve the tank and contact DAN Risk Mitigation at or +1-919-684-2948, Option 2.