Tsk tsk!!! You have a habit of asking the most embarrassing questions in the most innocent possible way!  :-)

Your point is well taken. What did I mean by "dangerous concentration" (or whatever term I used) ?

I meant more or less, that if you were forced to breathe that atmosphere only, and breathe it for a while, and not just catch a whiff of that atmosphere on your tongue, the results would be untoward. If you could see CO2 as plainly as we can see say NO2, you would be able to see that what you smelled comprised inhomogeneous wafting wisps of gas, not a uniform atmosphere of several percent of CO2. That also is why when you move the bottle away from your face, the smell goes away. Your average concentration of inhaled gas was quite safe.

Incidentally, in this respect CO2 differes from CO. It is now plain that CO does permanent damage to various tissues, particularly nervous tissue; CO2, as long as you stop before you get brain damage, diffuses pretty harmlessly out of your system.

Translatrix, I think a few of us are badly at cross purposes.

Firstly, you ask about acids that do not have sour tastes. Quite a few weak acids, compounds whose reactions with various bases are characteristically acid, affect the pH too weekly to have any significantly sour taste. Consider the taste of silicic acid for example. (I will not ask you to assess the taste of hydrocyanic acid, but I can assure you that its dominant taste is not one of acidity.)However, when I said that the acidity (as opposed to acid) was independent of taste, I had made the mistake of uncritically adopting the term used in the contribution to which I was replying. What I meant was to respond to the statement that the concentration of hydrogen ions generally determines the degree of sourness. (There are certain reservations even to this of course, because all sorts of factors, physiological and subjective, can affect tastes, including sourness. However, I do not think that any of us really see this as relevant to the matter under discussion.)

The point I was making (or trying to make) was that the anions of many acids affect their tastes in ways that have little to do with their pH, while their sourness is practically a function of their pH, down to a fairly low pH. Beyond a certain point one can no longer make fine distinctions of course.