Effects of Aerosols, Oxides of Nitrogen, and Oxidants on Human Health: Effect of Nitrogen Dioxide Exposure on Asthmatics' Response to a Bronchoconstricting Drug

摘要

This study was intended to test the hypothesis that exposure to nitrogen dioxide (NO2) at ambient level can increase asthmatics' susceptibility to bronchoconstriction brought about by other agents, even if the NO2 exposure itself has no measurable bronchoconstricting effect. Thirty-one asthmatic volunteers were exposed to 0.2 ppm NO2 and to clean air (control study) on separate occasions with order of exposure randomized. Exposure periods lasted two hours and included intermittent light exercise. Forced expiratory function and total respiratory resistance were measured pre- and post-exposure. Response to challenge with a bronchoconstrictor (forced expiratory and resistance measurements following graded doses of aerosolized methacholine chloride/physiological saline solution) was determined post-exposure. Symptom responses were determined from interview questionnaires administered before, during, and after exposure.