The use of humidity in asthmatic children.

Controversy exists as to the advisability of mist therapy in pulmonary disease. We studied the effects of several forms of humidity on asthmatic airways. Thirty-four children were tested over a period of 8 months as follows: (1) mist with a mean particle size of 3 mu was delivered for 30 min by an ultrasonic nebulizer to 11 children individually in a plastic tent; (2) to another 11 subjects in a tent, mist with a mean particle size of 10 mu was delivered by a jet nebulizer for 30 min;3) 15 patients in a croup room recieved for 30 min water droplets ranging from a microscopic fog to large rain particles (mean 16 mu) generated by a Melco natural fog generator; (4) 10 children were challenged with 3 solutions used commonly for the production of mist: distilled water, half-normal saline, and normal saline. Pulmonary functions were studied on each patient pre- and post-mist exposure. Approximately two thirds of the patients had a significant response, either improvement or deterioration, when challenged with the various forms of mist. No particular group trends were produced either by increasing the mean particle size of humidity, or by using solutions of increasing salinity.