68 Yo Male W/ Long Hx Of Asthma Well Controlled

68 yo male w/ long hx of asthma well controlled on Pulmicort 2 puffs BID. Recently started swimming (YMCA pool) for conditioning. Even with using Albuterol 2 puffs before swimming I become very dyspneic and develop wheezing with < one lap, mostly when doing the crawl (prone). Fewer sx w/ backstroke and no sx when sitting in the nearby hot-tub or walking on the deck. I have good tolerance w/ indoor rowing and treadmill (at my house). Guessing it's chlorine induced exercise asthma. Other thoughts and ideas how to treat? I'd like to swim! Thank you!