NITROGEN-DIOXIDE EXPOSURE IMPAIRS THE FREQUENCY OF THE MUCOCILIARY ACTIVITY IN HEALTHY-SUBJECTS

In previous studies, we have reported bronchoalveolar Lavage (BAL) fin dings following single and repeated exposures to NO2, Here, we present the first data an measurements of the frequency of the mucociliary ac tivity in healthy subjects Following exposure to NO2, Twenty four heal thy nonsmoking volunteers underwent fibreoptic bronchoscopy, during wh ich mucociliary activity was measured using an in vivo method based on a two-way fibreoptic system, to obtain baseline data, Two weeks later , the subjects were reinvestigated following NO2 exposure. Eight volun teers were investigated 45 min after a 20 min exposure to 1.5 ppm NO2 (Group A); eight subjects 45 min after a 20 min exposure to 3.5 ppm NO 2 (Group B); and eight subjects 24 h after a 4 h exposure to 3.5 ppm N O2 (Group C), No activity was detected in Group A or B 45 min after ex posure, in contrast to the easily identifiable mucociliary activity wa ves at the reference bronchoscopy, In group C, a significant elevation of the frequency of the mucociliary activity waves was seen at 24 h, It is concluded that short-term exposure to NO2 in man produces a sign ificant reduction in the mucociliary activity 45 min after exposure, T he effect ceases within 24 h, Further studies are needed to evaluate t he effects of repeated exposures with NO2 on mucociliary activity in m an.