Four people have been taken to hospital after being exposed to ‘excess chlorine’ at a day spa and gym in Derbyshire ... a mixture of some chemicals within the [pool's] systems'.

Rangan, V. Kasturi, and Sunru Yong. "Soren Chemical: Why is the New Swimming Pool Product Sinking (Brief Case)." Harvard Business School Teaching Note 104-190, April 2010. (Revised November 2011.) ...