There are three levels of contaminants that could contaminate your breathing gas:
- Those most commonly found in compressed gas like Carbon Monoxide (CO): Carbon dioxide (CO2), moisture (H2O), condensed oil, particles and odour
- Those found in certain geographic locations: volatile hydrocarbons and organic compounds, such as methane (CH4)
- Relatively rare but reported toxic substances: for example vapours from cleaning products and halogenated solvents, emissions from motor vehicles, suphur and nitrogen-based products and fumes
Carbon dioxide (CO2) in excessive quantities increases the rate of breathing and in deeper diving causes respiratory risk. It also leads to minor perceptive changes, discomfort, dizziness or stupor and in extreme cases it may cause unconsciousness and even death.
Excessive moisture can make regulators freeze or fail to open. It also enhances corrosion and rust of the cylinders, thus interacting with filtration elements reducing filtration efficiency and generating chemical odours causing nausea and respiratory irritation.
As for oil, especially the smaller particles create health concerns as they will not be removed by the bodys' clearance mechanisms, as happens to the larger particles. The retained oil particles can cause inflammation. Oil mists may also cause a significant fire hazard.
Dust is hazardous to both our lungs as well as to fine regulator parts.
All these contaminations imply awareness by the diver, diligence by the dive station and knowledge by all!