Dr Miller references a 2014 publication by Black et al,5 which reports five cases of extensive, painful, rapidly progressive pleural thickening among individuals exposed to Libby amphibole asbestos. We agree with Dr Miller that these findings are consistent with diffuse pleural thickening (DPT) and not with PP. In view of the extensive nature of their DPT, it is not surprising that these individuals had restrictive impairment. Furthermore, the chest pain experienced by these individuals could also cause “splinting” of the chest wall, limit chest wall excursion, and, therefore, contribute to the observed restrictive ventilatory impairment. Unfortunately, no pleural biopsies were performed, and, therefore, no correlation between the CT scan findings and the histopathologic characteristics of the painful, rapidly progressive DPT was reported. However, in comparison with these five cases, none of the miners in our study with NCTS, PP only on HRCT scan, or PP with interstitial fibrosis on HRCT scan had any evidence of DPT. We can find no scientific evidence that HRCT scan is unable to detect early, diffuse, lamellar pleural thickening that is extensive enough to cause restrictive ventilatory impairment, as suggested by Dr Miller. Additionally, the case series reported by Black et al5 is a descriptive study by design. It is important to note that descriptive studies do not have a comparison group and are unable to assess associations.6 Therefore, since the results of our study are based upon a comparison of miners with isolated PPs alone on HRCT scan to miners with NCTS studies, the five cases reported by Black et al5 have no scientific relevance to our conclusion that asbestos-related PPs alone have no significant effect on lung function in Libby vermiculite miners.