Because the force required to pull the air through a filter is greater than the force required to breath without. You have to pull the air into your body with more force. You’ll no longer be able to bring in the same amount of air by passively breathing. You need to active breathe.
The volume of air depends on how deep you breath in. It might take more force to breathe in as deeply if you're breathing through a filter, you'd need to exert more pressure, but the volume is independent of the force you're using to breathe it. If you were to blow up a balloon, it doesn't matter how fast or slow you fill it, the volume it will hold is the same. If that makes any sense.
Note to self: never create characters below 18 with ambiguous sexuality. Because you will be forced to explain what the hell their sexuality even is, but then you won't be able to because "no under 18". And now he seems like a frigging huge plot-hole in the center of your book and you can't do anything about it.
Uh. Not the way you stated it? If you meant, does it make it harder to breathe? Then, absolutely. As far as, how much air you can breathe in, or the composition of the air, nothing changes.
I said it limits you oxygen supplies. Not your oxygen. I obviously knew that is a respiratory issue and you need to apply more force to breathe in the same volume of air as without a mask, which lowers your lung volume.
I example come from a mountainous region and do cross country skiing, so I am familiar with a similar phenomenon. Our air is thinner, so sportsmen from northern countries like Sweden, Norwey, Russia, don't perform well here.
They are not used to the thin air, so our team wins often.
@UYScuti I wish I could do that .
Too bad my plot premise is build on him dying at 16. (Tldr, but there is this huge deal about age and perception of adulthood, plot-wise).
Like I said -- I put myself into the corner in so many different ways.
I should have fewer plot-relevant stuffs in my stories. Removing one can topple the entirety of the book,
It doesn't limit your oxygen specifically though. The ratio of atmospheric gases remains the same. The comparison to higher altitude is... hrm, similar in function but different in reasoning? At higher altitude, the ratios are the same but the pressure is less, meaning it takes more effort to get the same amount of oxygen in your lungs you'd have at sea level.
It's ... kind of confusing and I don't know a great way to explain it but, the whole percent of oxygen thing isn't even a metric that makes sense, it's more about the gas pressure? The best thing I can think of to exemplify this, is, humans can easily breathe at 20% atmospheric pressure if it's 100% oxygen. They did that for the space program, iirc.
I think you confuse concentration with the amount of oxygen you receive. The concentration will stay the same, but you won't receive the same amount as the lung volume is decreased.