toxic co2

So I was swapping out my co2 tank yesterday and pickin up a few things from my local hydro. A customer started askin me about bulbs, co2, and then spidermites. I told him so far I've never really had a bad mite problem (knock on wood) but I have heard good things about neem.and pyrethrin. Then the store employee chimed in "you could just open the valve on a co2 tank all the way till its empty and once it gets to like 10k ppm it will sufocate all the mites."

I didn't want to disagree with him right in front of the custoner because I don't know if that's common peactice? But I said, yeah you should probably go with some spray before you do that. And while I'm pretty sure it would kill the mites it could also kill you. I told him you want about 1500ppm to benefit your plants, and 2000 ppm will start to kill them. 5000 ppm will knock you out cold. I said I wouldn't use the co2 that way but if you do you need to be very careful, only let the co2 stay in there for a little while and then ventilate the area outside very well.

Then the clerk said "yeah just empty the bottle then ventilate it like an hour later"

Does anyone do this? It seems like an extremely dangerous, expensive and unnecesary way to kill mites. Especially when this guy was asking me basic questions about co2 and I'm sure he doesn't even have a regulator or ppm meter.

Im pretty sure that store clerk is trying to kill the guy ....

Below is taken from http://www.doomedglobe.com/Pages/co2_toxicity.htm but similar info can be found on OSHA and many other websites. I have never tried killing mites this way. I would also not sit in the room. But technically he should be fine after it airs out.
[FONT=book antiqua,times new roman,times][FONT=Book Antiqua,Times New Roman,Times]Basic Information about Concentrations of CO2 in Air[/FONT]

[/FONT] [FONT=book antiqua,times new roman,times]1,000,000 ppm of a gas = 100 % concentration of the gas. Therefore, 10,000 ppm of a gas in air is a 1% concentration. [/FONT] [FONT=book antiqua,times new roman,times]At 1% concentration of carbon dioxide CO2 (10,000 ppm) and under continuous exposure at that level, such as in an auditorium filled with occupants and poor fresh air ventilation, some occupants are likely to feel drowsy. [/FONT] [FONT=book antiqua,times new roman,times]The concentration of carbon dioxide must be over about 2% (20,000 ppm) before most people are aware of its presence unless the odor of an associated material (auto exhaust or fermenting yeast, for instance) is present at lower concentrations. [/FONT] [FONT=book antiqua,times new roman,times]Above 2%, carbon dioxide may cause a feeling of heaviness in the chest and/or more frequent and deeper respirations. [/FONT] [FONT=book antiqua,times new roman,times]If exposure continues at that level for several hours, minimal "acidosis" (an acid condition of the blood) may occur but more frequently is absent. [/FONT] [FONT=book antiqua,times new roman,times]Breathing rate doubles at 3% (30,000 ppm)CO2 and is four times the normal rate at 5% (50,000 ppm)CO2. [/FONT] [FONT=book antiqua,times new roman,times]Toxic levels of carbon dioxide: at levels above 5%, concentration CO2 is directly toxic. [At lower levels we may be seeing effects of a reduction in the relative amount of oxygen rather than direct toxicity of CO2.][/FONT] [FONT=book antiqua,times new roman,times] Symptoms of high or prolonged exposure to carbon dioxide include headache, increased heart rate, dizziness, fatigue, rapid breathing, visual and hearing dysfunctions. Exposure to higher levels may cause unconsciousness or death within minutes of exposure.
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I have used this and recommended it. Obviously, you open the bottle and then leave the room. after an hour, you open the room and vent it for another hour or 2. the plants can handle it as long as there not exposed for more then a couple hrs.

damn really thanks for that info guys I never would have thought.

So in my 560 sq. Ft. Room it takes .672 cu ft. to bring the co2 to 1500 ppm. Which is .15%

1 lb co2 displaces 8.7 cu ft of co2 so in a 20lb bottle there's 174 cu. Ft.

That's enough to bring the room to 1500 ppm 116 times that's 17%. My math is right but the process I used may be wrong. I'm no mathmatician but it still seems far past the lethal dose.

Obviously you wouldn't sit in the room with it but still seems like bad info to give so generally without any warning or plan on how to do it safely.