Considering an atmosphere of just N2 and O2:

O2 reduced from 21% to 14% by volume. First perceptible signs with increased rate and volume of breathing, accelerated pulse rate and diminished ability to pay attention.

O2 concetration between 14% to 10% by volume. Consciousness continues, but judgment becomes faulty. Rapid fatigue following exertion. Emotions affected, in particular ill temper is easily aroused.

O2 reduced from 10% to 6% by volume. Can cause nausea and vomiting. Loss of ability to perform any vigorous movement or even move at all. Often the victim may not be aware that anything is wrong until collapsing and being unable to walk or crawl. Even is resuscitation is possible, there may be permanent brain damage.

O2 reduced below 6% by volume. Gasping breath. Convulsive movements may occur. Breathing stops, but heart may continue beating for a few minutes. Ultimately death.

- Smith, G.K., 1997, Naked flame tests for CO2 in limestone caves and the effect of CO2 and O2 on humans: Australian Speleological Federation, Proceedings of the 21st Biennial Conference of the Australian Speleological Federation, pp. 40-52.

Also see Smith, G.K., Caves, carbon dioxide, and you: same volume

I was in the city today and found a light very similar to the Life Gear one.

This light is a Garrity Battery Operated Glo Lite and it cost $2.00 at a discount store.

I just now opened and tested the green version and it throws more light than a regular glow stick, with an easy on/off switch, but no built-in whistle.

The light is sealed with an o-ring so it cannot be disassembled for use as a white LED light and it comes with a break-away lanyard.

The packaging states that it is good for 24 to 36 hours, I will probably buy a few to use when the boat or trailer lights give me problems.

Thanks for posting them TeacherRO, I would not have known what they were if I had not read your post.

Mike

Saw those at Target. They're neat but the the choice of battery and lack of water resistance kind of blows. A AA version would be handy.

Dang I never thought about some of this stuff but have been a big fan of Krill lights. The extreme 180 degree green puts out as much light as a freshly cracked chem light for over 50 hours. I also use the red 360 degree when I travel. I place it on a table or something so that I don't bump into something as I stumble around in the dark.

I used to have one of those and that's exactly what I did by just snapping off the plastic assembly! *chuckle*

I bought a couple 3 packs of similar LED Light Sticks at Brigade Quarter Masters about 3 years ago. The batteries in these Glow Sticks can be replaced, and the tube can be removed so that you can use the LED as a flashlight.

I gave away 2, but still have 2 in my BOB and 2 in my car that still worked well during the last check.

I like the Life gear glow stick as a safety light - to mark a campsite or to act as a night light for a room when the power is out. The only drawback I can see for either of these uses is the non-standard batteries. Is there a 200 hour flashlight with aa batts?

My Nitecore D10 runs for 55 hours (on low) on a single AA. To get 200 hours I'd carry 3 spares.

Actually I measured that using an Eneloop, with a capacity of around 2000mAh. Lithium AAs claim a capacity of 2900mAh, so using those you might only need 2 spares.

Why do you need 200 hours anyway? Do you expect to get stuck in a cave for 8 days continuous? With a battery device, you can switch it off during daylight or when you're asleep.

If I remember correctly (it has been since 1998) the 16% value has something to do with entering confined spaces. I remember our "bang meters" checked not only for bad gasses (things that go BANG), but for O2. Seems as though the 16% value was considered the do not enter threshold without supplemental air.

Said meters actually checked for all sorts of things, and were able to determine the fuel/air mix for combustibility.

But like I said..... This is operating on 11 year old memories.

Has anyone tried these lights yet? Thinking of getting some for lights out emergencies and camping.