Out of the blue and into the pink

A new litmus test for chlorine gas exposure

MJA 1997; 167: 651  

To the Editor: A 40-year-old man arrived at the emergency department by ambulance in respiratory distress. In his duties as a hotel maintenance worker, he had been mixing swimming pool chemicals in a dark, confined space. Inadvertently, he had mixed liquid pool "chlorine" (sodium hypochlorite) with a hydrochloric acid solution, forming an irritating yellow-green gas. Despite a brief exposure, he rapidly developed eye irritation, burning in his oropharynx, cough and chest pain. He noticed that the keys in his pocket had turned a dull colour. On arrival, about 20 minutes after the exposure, he had an irritating cough, but his vital signs were normal, oxygen saturation was 99%, and his chest was clear to auscultation. His clothing smelt of chlorine and was removed to prevent skin irritation. On removing his white overalls, it was noticed that his blue underpants had changed colour to a pink-mauve hue. Although he suffered acute embarrassment, he developed no acute clinical or radiographic signs and was discharged well after several hours' observation. Chlorine gas exposure is not an uncommon hazard of mixing household cleaners or pool chemicals. The addition of an acid to a chloride-containing base releases chlorine gas in an exothermic reaction. Chlorine gas is highly water soluble and on moist surfaces is transformed into hydrochloric acid and an oxygen radical. This mechanism explains the clinical manifestations, with the hydrochloric acid causing immediate irritation to mucosal surfaces, leading to lacrimation, burning sensations and cough. These symptoms usually serve as a warning to the victim to move away from the gas to prevent the more serious sequelae of laryngeal oedema, bronchospasm and adult respiratory distress syndrome. Presumably in this case, the elaboration of acid in the sweaty confines of his true-blue Y-fronts mimicked the classic pH indicator reaction of litmus paper. Perhaps he should have worn his underpants on the outside! Tim C Green Staff Specialist, Emergency Department, Royal Prince Alfred Hospital Missenden Road, Camperdown, NSW 2050. E-mail: timgreenATmpx.com.au Reference: Hoffman RS. Toxic inhalations. In: Rosen P, Barkin R, et al., editors. Emergency medicine -- concepts and clinical practice. 3rd ed. 1992: 2673-2682.