The rapid spread of the coronavirus (COVID-19) pandemic affected the economy, trade, transport, health care, social services, and other sectors. To control the rapid dispersion of the virus, most countries imposed national lockdowns and social distancing policies. This led to reduced industrial, commercial, and human activities, followed by lower air pollution emissions, which caused air quality improvement. Air pollution monitoring data from the European Environment Agency (EEA) datasets were used to investigate how lockdown policies affected air quality changes in the period before and during the COVID-19 lockdown, comparing to the same periods in 2018 and 2019, along with an assessment of the Index of Production variation impact to air pollution changes during the pandemic in 2020. Analysis results show that industrial and mobility activities were lower in the period of the lockdown along with the reduced selected pollutant NO₂, PM_2.5, PM₁₀ emissions by approximately 20–40% in 2020.

Cities are leading in the implementation of circular economy (CE) principles and sustainable development due to the concentration of knowledge, resources and technology while remaining the highest consumers and producers of resources. CE, urban metabolism (UM) and industrial symbiosis (IS) offer a new more holistic approach based on material and energy flow analysis and materials recovery from waste by creating IS networks to support a new circular urban system (CUM) which contrast to the traditional linear extract-produce-use-dispose model of economic systems. In this paper, we present the concepts of CE, IS and CUM and how the new framework could improve cities transition to sustainability and CE, with detailed CE and IS indicators analysis. We introduce the relations between IS, CE and UM concepts, how they can be used and monitored in the CUM framework. CUM can help unite urban planners, the city’s governance and the business sector to promote collaboration across the city to improve future sustainability and circularity by closing loops.

The identification of the main steps for the creation of a unified ecosystem from the institutional point of view and the framework for ecosystem design is presented and discussed. Based on the expertise and the knowledge gained during the time when the ELISE project had been implemented, a unified Kaunas city ecosystem is being designed using the Ecosystem Map method. As the review of the ELISE project reports helped to identify the main steps of each project partner in building ecosystems’ networks, Kaunas city chose to create a co-Creation Hub (c-CH), which is the first step in developing an ecosystem management model. The main tasks of such a hub are listed, and should involve the preparation of a long-term action plan involving not only the coordination of the stakeholder meetings, organisation of seminars, the preparation of new materials, and methodology but also the development of a clear strategy for each stakeholder based on national economy and government and municipality policies. The role of the c-CH is to ensure the ease of cooperation and knowledge distribution among stakeholders within the city, public authorities, and the national government. This approach could become a fundamental background tool for the regional and/or city municipal and stakeholder-based creation and development of unified ecosystem development.