I have asthma [asthma isn't binary, the symptoms arent always present, everyones triggers are different], and competed in swimming at the HS and college level successfully. Although I think I gravitated towards the sprints early as a result of this /tangent.
I'd get a little bit more winded than most when I was younger and trying to figure out what was wrong with me. Coaches guided me into sprint workouts to stay in the sport. Turns out it I had air pollution [LA suburb] and seasonal allergy asthma triggers.
Not a rare combination. Just a little pharmaceutical magic during the spring and no symptoms present.
That DOESNT mean that on race day I wouldnt have a problem, though. It was always a threat, I just have a really mild case of asthma so an outright event only occurs about 1-2x/yr at most for me even today.
On a given workout if I've taken my allergy meds over the previous week I have like a 1% chance of having an attack or something.
But still it isnt zero. As an adult I had an asthma attack during the Santa Rosa 70.3 based on pollen counts that I just couldnt handle even medicated. Was a mild attack, I just hobbyjogged it out and didnt actually notice on the bike that I was in arrest. On the run it became obvious though.