## 1 Introduction
The benefits of biomass densification were widely presented and discussed in recent review papers [23; 24; 25], including the integration of torrefaction with pelletization [26]. Pelletizing technology is mature from production to end-use, and therefore, pelletized CRDF can help with adopting it for wide-scale use in waste management. Our recent research [27] shows that more than 80 VOCs are being emitted from CRDF, including toxic derivatives of benzene or toluene. Thus, practical solutions for the mitigation of VOCs emissions from CRDF are needed, especially applicable to storage and handling when workers are exposed to emitted compounds [28]. One of the solutions of VOC emission from CRDF may be pelletization. Studies on VOC emissions during wood pelletization tend to focus on the work environment and measure concentrations of substances in the air at pelleting plants [29; 30; 31]. The quantitative estimations of emissions per ton of pellets produced have been explored only in a few studies [32; 33]. [PERSON] and [PERSON] [22] determined that during wood pellet production, only \(\sim\)30-40% of the initial terpen remain in the wood after dying, 20-30% remain after grinding, and 10%-15% remain after pelleting. It has been determined that wood pelletization itself causes the emission of VOCs [22]. However, the VOC emissions during CRDF pelletization have not been studied yet. In our recent study, we tested the effect of pre-treatment on VOCs emission from the CRDF in densified and bulk (powdery) form. We examined the influence of two scenarios of CRDF densification: pelletization, and pelletization with a binder (\"water glass\") on the kinetics of individual VOC emissions [34]. We determined that pelletization of CRDF was more effective in VOCs emission mitigation than grinding or pelletization with a binder. However, the important aspect is the application of CRDF pelletization to typical operational procedures of RDF terfaction plants. As the RDF terfaction technology is currently under development, a full-scale RDF terfaction plant has not been in operation yet. However, it is reasonable to assume that within the near future, new technology will be implemented at full-scale. Therefore, proposed tests on VOCs emission rates from CRDF during storage may have great importance for preparing the investment plans of the future RDF terfaction plants, including standard operating procedures, environmental impact assessments reports, and occupational safety and health protocols. It could open new research niches for in-depth understanding and development of fundamental knowledge about the relationship between the CRDF structure and its properties, and its implication in occupational safety and health protocols. As RDF terfaction plants do not exist yet, by analogy, we applied to the typical conditions of RDF storage [35]. In the typical operation procedure at RDF production plants, the longest possible period of RDF storage is four days (e.g., RDF produced on Friday has to be in storage until Monday for transportation). Usually, the produced RDF, due to the risk of self-heating and, in consequence, fire and even explosion [20], is not stored longer than a couple of days. Similarly, wood pellets storage is not recommended to be longer than several days [36]. By analogy, in this paper, we focused on the proposed four days of CRDF storage as being the 'worst case' scenario for a production facility and explored VOC emissions. For this reason, we proposed to compare the VOCs emission rates from the ground and pelletized CRDF during four days of storage and to identify the VOCs associated with the highest emissions and VOCs posing imminent danger to safety and health [37]. As the next step of RDF terfaction technology, the development from fundamental to applied research of the simulation of VOCs concentration in the headspace of the storage bin was proposed, with a comparison of the Polish and USA occupational health standard threshold values for inhalation of VOCs.