Caving and the dangers of Foul Air(Bad Air)

Caving is a thrilling adventure activity that we encourage everyone to try out at least once. Self explore caving is especially thrilling, There is just something about putting a helmet on, grabbing a torch and venturing into the darkness. Not having an experienced guide however brings some dangers into the adventure. We’re going to discuss one of the more dangerous but less obvious dangers with self guided caving, Foul Air.

Foul air (also known as Bad Air) is the lesser known, not as often considered danger of caving. Foul air is a build up of carbon dioxide to a concentration of above 1% of the air (The normal makeup of carbon dioxide in the air is roughly 0.2%). Any gas heavier than oxygen can be a contributor to foul air, but it is almost always due to carbon dioxide. For this reason vertical caves are much more susceptible to contain foul air opposed to the more accessible horizontal cave. Due to low air flow through vertical caves carbon dioxide builds up in invisible odourless pools.

The fact that these pockets are odourless and invisible is what makes them so dangerous. If you’re not aware of them you’d never even know until it was too late. One of the most immediate tell tale signs of foul air is headaches. Followed by drowsiness then potentially loss of conciseness and then.. well.. death.

There are proactive measures you can take when caving to detect foul air. The expensive but effect method is to purchase electronic air quality detectors, the cheap and also effective method is that you can take a lighter or a box of matches. When you enter the cave, where it too dark to see without a torch but still early enough in that there is no risk of foul air, light a match and get a gauge of how well it burns and how bright. As you descend, light a match, if the match starts to become dim you are detecting higher levels of CO2 in the air. If the match goes out immediately after lighting then you are in a dangerous amount of carbon dioxide and should ascend back up the cave as quickly as safely possible.  Using the lighter follows the same concept, as CO2 builds up, the flame will become more dim.

For a detailed summary of what affects increase CO2 and decreased O2 has on the body I recommend reading this page.

Other essentials when caving

One other thing that we highly recommend to have when caving is a helmet, nothing will ruin your caving adventure more than banging your head on the cave roof over and over again.

Here is your complete checklist of what to take when caving

  • Matches/lighter
  • Helmet
  • Head torch
  • Hand held torch
  • Extra batteries
  • Food/water


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