Originally Posted by newsace
so I'm wondering if there's something about the chemicals used to make the shirt that's reacting with sweat.
This is my vote. With polyester shirts, after a hard ride and some good sweating, they can have a strong ammonia smell and it can actually make it difficult for me to breathe. All my polyester biking/hiking shirts do this after time. All I can think of is there's something in them that reacts with my sweat, making an ammonia smell.