Recent research done by Dr. Arthur J. Williams of the Sports Science Institute of South Africa indicates that clorine in pools may cause breathing problems. The study shows that even lower than recommended levels of clorine can cause breathing difficulties after only a few minutes (approximately 6-8) of swimming. These breathing difficulties show symtoms consistent with exercise-induced bronchocontriction (EIB) or exercise induced asthma. The study contained two groups. One group consisted of 20 trained swimmers with no EIB history while the other contained 21 with a history of EIB. These groups were tested in four situation including clorine-free water and exercising next to clorinated water. Sixty percent of the swimmers regardless of history experienced EIB. The concentrations tested were all below the genreally recommended amount of 2.0 PPM. Dr. Williams recommended that chlorine concentration be kept below 0.5PPM.