The influence of ozone-containing atmosphere on the track-etching parameters of cellulose nitrate, cellulose acetate, polycarbonate and polyvinyl chloride sheets was studied. Evidence of the increase of registration sensitivity was found for all plastics investigated. The effects of ozone treatment on the tracks of both lightly and heavily ionizing nuclear particles are discussed. Experimental data are given on the variations of the etching properties of bulk material and latent tracks as a function of storage times in ozone atmosphere. The observations indicate that in any effect where there is a possibility of ozone production (e.g. with plastic detectors placed in spark discharge or exposed to ultraviolet radiation) the sensitivity variation due to ozone effect cannot be neglected.