Is it easy to take it down to take a sip of water then back up? Or do you need to remove it all the way to be able to take a drink?

Hello, thank you for your question. It should be quite easy, the side cinch straps could probably be left although you may need to adjust the velcro at the back. Kind regards, Fitzy Shop.

Will this product warm the air prior to breathing?

Hello, thank you for your question. The venting at the front will not warm the air markedly before breathing. Kind regards, Fitzy Shop.

How can this product prevent glasses fog-up if it doesn't have a tight contour fit around the bridge of the nose?

Hello, thank you for your question. This mask may help prevent goggle fog (ski goggles) but we do not claim that it prevents glasses fogging up. Please let us know if you have any other questions, we are happy to help. Kind regards, Fitzy Shop.

Can the piece over the bridge of the nose be bent for more seal (like dust mask)? Would help prevent glasses from fogging up.

Hello, thank you for your question. This mask does not have a piece over the bridge of the nose that can be bent. The mask may help prevent goggle fog (ski goggles) but we do not claim that it prevents glasses fogging up. Please let us know if you have any other questions, we are happy to help. Kind regards, Fitzy Shop.