he harmful effects of SHS on HRCT signs were found to be dependent on the dose, the average score increasing by 0.005 for each pack-year of exposure. Most of the participants of the present study were construction workers working mainly outdoors, which may have diluted their SHS exposure at work, and this, along with the limited sample size, may have influenced our ability to detect any possible association between SHS and emphysema or other radiological signs.