I know54 treated in hospital after inhaling leaked chlorine gas at SAFRA club For a moment there I thought Singapore was under attacked by bio-terrorist.It turns out they accidentially poured the Sodium Hypochlorite, use to balance the neutrality of the water(NaOCl) into the HCL, use to bring it to more acidity if the swimming pool water is too alkaline to produce Sodium hydroxide and chlorine gas. NaOCl + HCl ==> NaOH + Cl2 Chlorine gas is poisonous. Chlorine gas was used in WW1 by the germans to cause respiratory damage to the allied soldiers. It can destroy the respiratory organs of its victims and this led to a slow death by asphyxiation. If I'm one of the people involved in the incident, I'll sue the Safra club for causing bodily damages and emotionally damages. What's stopping the terrorist from sneaking into any swimming pool to mess with these chemicals?