I never wear gloves (soon to change) and have felt the effects of Zoos. Any time I move around my colonies, or attempt to frag a certain colony, my chest gets tight, and I have shortness of breath. It's never lasted more than about 15 minutes, and has never been enough to really scare me, but now I'm reconsidering my disregard for concern.
I've also had a case of what I thought was food poisoning, which now makes me second guess that. I haven't vomited in several years (over 4) and one day out of the blue (don't remember my tank tasks for the day) I get sick, and start throwing up. I chalk it up to food poisoning, but I'm fairly new to the hobby, and it was around the time of a tanks swap.
I also have had incidents where my arm felt numb for almost a full day, just kind of achy, throbby and numb. I love zoos, guess it's time for gloves.