Assuming this is "blowing out fire" as in blowing fire so that it goes out, and not as in katon jutsu...
Clothing/material has small holes in it, which allows you to blow air through it... Granted any amount you blow will be severely decreased, but still, these people shoot out a lakes worth of water by making shapes with their hands. It's not surprising he can blow out fire...
Even still, it's not like water or fire is contained in the lungs for the jutsu caster to blow out, the chakra is changed into fire (or water, air, etc) in front of the area it is coming out of. Otherwise, the jutsu caster would have some really poor lips...