## 2. Incineration in the Iberian Countries  
In Portugal, although the management system heavily relies on landfills, important progress has been observed towards more sustainable technologies. Indeed, landfilled waste decreased from 72% to 50%, and the waste recycled (including composting) increased from 8% to 31%, between 2002 and 2018 (Figure 1a). On the other hand, although an increase (from 18% to 26%) has been observed at the EU level for incinerated waste, in Portugal almost a consistent 20% (nearly 1 Mt-about 100 kg per capita) of waste is incinerated [9; 16]. In Spain, despite the measures promoted by public administrations, landfill is also still the main option for the final management of MSW (Figure 1b). In the past 15 years, the contribution of landfills as a fate for wastes decreased by only 10% (from 61% to 51%). Consequently, all other treatment options increased slightly but much less than expected, with 18% of materials recycled from MSW in 2018, 13% incinerated with energy recovery, and only 17% of the organic fraction of MSW composted or digested in anaerobic bioreactors [9]. Despite the guidelines and hierarchy established by the European Parliament for the treatment of waste (Directive 2008/98/EC), in which energy recovery from MSW is prioritized over its landfilling, there has generally been a lack of political support and willingness in both countries to increase national incineration capacity. This is probably due to public pressure based on technically and scientifically unfounded fears (e.g., linked to emissions, which are controlled under strict limit values in the EU), misinformation (e.g., the idea that European funds do not support this field), or the hypothesis that incineration will not be necessary if prevention and recycling are implemented instead. Indeed, the Portuguese Association of Entities for Energy Recovery from MSW (AVALER) and the Spanish Association for Energy Recovery from MSW Companies (AEVERSU), along with the general waste management industry, have argued that one of the main challenges for the development of the waste sector is the deficient capacity for WtE that could avoid disposal in landfills. As a result of the rising production of waste and the fact that Portugal and Spain continue to landfill about half of their MSW, it is expected that the landfill capacity in most of the national territories will be used up in the near future since new landfills are not planned. WtE creates a final valorizing destination for non-recyclable waste, avoiding waste exportation with the corresponding environmental and financial costs, and may contribute to achieving EU and National landfilling targets. In this context, AVALER made a proposal within the framework of a new Strategic Plan for waste management with an implementation horizon set to 2030 (currently in discussion). This plan intends to create the conditions for valorizing all waste with recovery potential, using a combination of quality recycling and energy recovery of non-recyclable waste [17]. Recycling cannot be 100% achieved due to the dissipative losses of materials between the life-cycle stages of manufacturing and end-of-life, to the possible loss of the original properties of materials, and to some harmful substances that must be separated to protect human health and the environment. On the other hand, WtE eliminates toxic organic substances and mineralizes the organic components, working as a sink for organic materials (some of them environmental pollutants) [1,2]. Thus, incineration does not substitute recycling but rather supports high-quality recycling [10]. Furthermore, incineration is considered a sanitary method for the treatment of MSW [18] and it works as a buffer for the system in the case of unforeseen events, such as the COVID-19 pandemic, due to its ability to destroy pathogens potentially present in MSW.