Because i have atopic dermatitis, when i work out or run, (if i sweat, i get allergic reaction) what kind of exercise i could do to prevent humidity ?

Swimming: Swimming may be a good choice for you, but only if the pool chemicals are not one of the triggers for you atopic dermatitis. Aside from that, most exercise involves sweating. But even a nice walk can be good exercise - do it very early in morning or after sunset when it is cooler, and wear cotton clothes that will absorb sweat you produce. Best of luck to you!