*3.1. Test Chamber Experiments: Characterization of VOC Emissions and Determination of Emission Rates (ERs)*

VOCs reported in Table 2 represent the pattern of gaseous pollutants identified and quantified by test chamber experiments performed under controlled conditions and with the electric bags on 'not-heating mode'. VOC emission data are expressed as emission rates (ERs) (ng/h) and chamber air concentrations (μg/m3), with the latter reported as an average value of duplicate measurements corrected for chamber background. If a preliminary comparison among the investigated items is done, emission testing of the heating bag 'polyester-brand A' resulted in the highest total VOC chamber concentration at 72 h sampling time. More specifically, for 'polyester-brand A' the total emission expressed as the sum of concentrations of VOCs (Σ VOCs, μg/m3) was equal to 437.0 μg/m3, one order of magnitude higher than those obtained for 'PVC-brand B' (21.1 μg/m3) and 'PVC-brand C' (19.6 μg/m3). In detail, VOC chamber concentrations for 'polyester-brand A' ranged from 0.7 μg/m3 (benzene) to 360.5 μg/m<sup>3</sup> (naphthalene), whilst 1,2-dichloroethane and tetrachloroethene were both below the LOQ of the applied analytical technique. As a result, the emission rates (ERs, ng/h), calculated by equation (1), ranged from 18 ng/h to 9013 ng/h. VOC chamber concentrations and ERs for 'PVC-brand B' ranged from 0.6 μg/m<sup>3</sup> (benzene) to 6.8 μg/m<sup>3</sup> (toluene) and from 15 to 171 ng/h, respectively. Finally, VOC chamber concentrations for 'PVC-brand C' were in the range from 0.7 μg/m3 (i.e., 1,2-dichloroethane and 1,2,3-trimethylbenzene) to 4.8 μg/m3 (toluene) and, as a result, ER values ranged from a minimum value of 16 ng/h to a maximum value of 121 ng/h. For both 'PVC-brand B' and 'PVC-brand C', 2-ethyltoluene, 3-ethyltoluene, 4-isopropyltoluene and acetophenone were below the LOQ. Additionally, 1,2-dicloroethane and benzene were below the LOQ for 'PVC-brand B' and 'PVC-brand C', respectively. Therefore, taking into account all the collected data, it is possible to observe that, whilst VOC emissions from PVC items resulted to be comparable in terms of concentration levels (for both the heating bags, chamber concentrations were generally below 10 μg/m3), the most remarkable result was regarding the naphthalene emission from 'polyester-brand A', which resulted in a chamber concentration at 72 h equal to 360.5 μg/m3. Previously published studies have already highlighted that materials and consumer products are responsible for naphthalene emissions and may significantly contribute to naphthalene inhalation exposure inside indoor environments [28]. Screening investigations reported by Kang et al. (2012) aimed at the identification of sources revealed that, disregarding specific sources intended to contain pure crystalline naphthalene (e.g., mothballs), interior materials as well as several consumer products may unintentionally emit naphthalene. The aforementioned study also highlighted that, across the interior materials investigated, mats consisting of PVC-coated polyester material showed the highest naphthalene emission factor, confirming that naphthalene is involved in the production and finishing of these polymeric materials. Naphthalene is,

indeed, primarily used as a chemical intermediate for phthalic anhydride and naphthalene sulphonate production, both involved in the industry manufacture of plasticizers, dyes and rubber formulations. Moreover, according to the existing literature, aromatic hydrocarbon release from polymeric materials (PVC, polyester) used as covering for interior materials such as wallpapers and flooring materials as well as polymeric items such as children toys may be mainly explained by taking into account the use of specific solvents in the manufacturing process such as toluene, ethylbenzene, isopropylbenzene and potential related impurities [4,19,29].

**Table 2.** Test chamber concentrations (μg/m3) at 72 h and related emission rates (ERs, ng/h) for VOCs emitted by the investigated bags on 'not-heating mode'.

