**1. Introduction**

Volatile Organic Compound (VOC) emissions from indoor materials and consumer products have become a subject of concern among indoor air scientists [1–4]. VOCs released into indoor air from a wide range of materials and products may deteriorate Indoor Air Quality (IAQ), resulting in odor annoyance and general discomfort for building occupants as well as adverse effects on human health [5–11]. So far, the interest of indoor air scientists in this issue has been mainly motivated by the need to improve the knowledge regarding sources and their emission characteristics in both private and public settings, to investigate further the physical and chemical interactions of emitted pollutants in indoor air, and to develop innovative methodological approaches for the evaluation of emissions and their potential impacts on human health. Building and interior materials have been widely investigated in terms of VOC emissions, as highlighted by an extensive literature in the field. On the contrary, limited data are available on consumer product emissions and related inhalation exposure for end users. Recently published studies have pointed out that consumer products and polymer-based items may release VOCs and odors indoors, contributing significantly to the overall VOC exposure of consumers and building occupants [12–17]. Moreover, complaints about odor annoyance from polymer-based

consumer products have enhanced the need for in-depth investigations aimed at elucidating emission patterns and characteristics. In this regard, investigations carried out on selected polymer-based items such as plastic utensils and children's toys highlighted that VOC emissions are related to the release of residual solvents and monomers from the material polymeric structure and/or the release of additives (i.e., plasticizers, inks) following surface-applied finishing processes such as coloring and printing [18–21]. VOC emissions from materials and products (i.e., building materials, furnishings, finishing products etc.) are conventionally evaluated by means of test emission chambers according to well-established procedures, standardized by the European Committee for Standardization (CEN) and by the International Organization for Standardization (ISO) [22,23]. More specifically, identification and quantification of VOCs from single or multiple sources requires emission testing inside test chambers, over a defined timescale and with selected micro-environmental parameters (i.e., temperature, relative humidity, air exchange rate) [24]. Small-scale emission testing generally fits investigation purposes when the determination of emission rates from specific materials and products is required, while large-scale experiments are more suitable for simulating realistic inhalation exposure scenarios for building occupants and consumers due to material installation and/or product use. However, some considerations regarding this point are necessary. Although testing procedures are standardized to obtain reliable data on emission characteristics, they may reveal some limitations when applied to consumer products, especially if the evaluation of emissions under actual conditions of use is required. Indeed, it is important to point out that VOC emission characteristics, in terms of the pattern of generated compounds and extent of the emission, may significantly vary during product/item use, particularly if the use involves combustion and/or heating, resulting in exposure scenarios being substantially different [25]. This typology of indoor sources is characterized by short-term emission patterns during the actual use and requires a realistic scenario to be simulated in the test emission chamber. Therefore, in these cases, the integration of conventional procedures (e.g., standardized emission testing) with complementary and innovative methodological approaches can be strategic to answer key questions on VOC emissions under effective conditions of use. The main objective of the present study is the evaluation of VOC emissions from a personal care polymer-based item, an electric heating bag, commonly used to relieve stress and reduce muscle and joint pain. The investigated item must be electrically supplied, therefore emission characteristics may significantly change under conditions of use. For this purpose, the present paper proposes a strategic methodological approach for the estimation of the inhalation exposure to VOCs emitted by the investigated items on 'heating mode' in a real setting, starting from emission data obtained through standardized methods and under controlled conditions. The experimental activity involved test emission chamber and dynamic head-space investigations on three different heating bags, commercially available at the moment of the study and also responsible for odor annoyance at ambient temperature.

Data collected were useful for the estimation of VOC emission rates (ERs) under actual conditions of use and, as a result, for the estimation of the indoor concentrations representative of short-term exposure related to the item use during the first life-cycle period in a realistic setting (e.g., reference room of EU standardized evaluation schemes), allowing the simulation of a near-to-real exposure scenario.
