On the thermal breakdown of tremolite: a new method for distinguishing between asbestos and non-asbestos tremolite samples

Tremolite asbestos is classified as a carcinogenic substance because it can cause a number of diseases when inhaled. The tremolite breakdown temperature reported in the literature varies by about 280 °C and has not been fully characterized from a thermal perspective. In order to address this gap in the scientific literature, a systematic study of the thermal behavior was conducted of twelve tremolite samples using thermogravimetric and differential scanning calorimetry (TG/DSC) supplemented by PXRD, SEM/EDS, EPMA/EDS and TEM/EDS. Tremolite samples from different locations (i.e., Italy, Switzerland and USA) were selected for their social, health, economic and industrial relevance. Data reveal that the breakdown of tremolite occurs in a temperature range of about 200 °C. The implications of this finding are discussed in light of chemical and morphological data. Variations in the breakdown temperature are mainly ascribed to the morphology of the studied tremolite samples. This study suggests that thermal analysis could be a new method for effectively distinguishing between asbestos and non-asbestos tremolite samples. The thermal oxidation of iron in the various tremolite samples occurs at different temperatures, and hence reduction of tremolite reactivity through the thermal oxidation of iron should be planned on a sample-by-sample basis. Given the different temperatures recorded for tremolite breakdown, the effectively detecting the presence of tremolite in bulk natural samples by thermal analysis can only be carried out if a thermogram of that specific sample is available. This is an important issue, especially in areas with a natural occurrence of asbestos outcrops.