sustainability Article Does Staying at Home during the COVID-19 Pandemic Help Reduce CO 2 Emissions? Kentaka Aruga 1, * , Md. Monirul Islam 2,3 and Arifa Jannat 3,4   Citation: Aruga, K.; Islam, M.M.; Jannat, A. Does Staying at Home during the COVID-19 Help Reduce CO 2 Emissions? Sustainability 2021, 13, 8534. https:// doi.org/10.3390/ su13158534 Academic Editor: Giovanni Leonardi Received: 17 June 2021 Accepted: 27 July 2021 Published: 30 July 2021 Publisher’s Note: MDPI stays neutral with regard to jurisdictional claims in published maps and institutional affil- iations. Copyright: © 2021 by the authors. Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (https:// creativecommons.org/licenses/by/ 4.0/). 1 Graduate School of Humanities and Social Sciences, Saitama University, 255 Shimo-Okubo, Sakura-ku, Saitama 338-8570, Japan 2 Department of Agricultural Economics, Bangladesh Agricultural University, Mymensingh 2202, Bangladesh; monir.bau_96@yahoo.com 3 Graduate School of Life and Environmental Sciences, University of Tsukuba, Tsukuba 305-8572, Japan; arifaecon_bau@yahoo.com 4 Institute of Agribusiness and Development Studies, Bangladesh Agricultural University, Mymensingh 2202, Bangladesh * Correspondence: aruga@mail.saitama-u.ac.jp Abstract: Quarantining at home during the COVID-19 pandemic significantly restricted human mobility such as visits to parks, grocery stores, workplaces, retail places, and transit stations. In this research, we analyzed how the changes in human mobility during the first wave of the COVID-19 pandemic, from February to April 2020 (i.e., between 17 February and 30 April 2020), affected the daily CO 2 emissions for countries having a high number of coronavirus cases at that time. Our daily time-series analyses indicated that when average hours spent at home increased, the amount of daily CO 2 emissions declined significantly. The findings suggest that for all three countries (the US, India, and France), a 1% increase in the average duration spent in residential areas reduced daily CO 2 emissions by 0.17 Mt, 0.10 Mt, and 0.01 Mt, respectively, during the first wave period. Thus, confining people into their homes contributes to cutting down CO 2 emissions remarkably. However, the study also reveals those activities such as visiting parks and going grocery shopping increase CO 2 emissions, suggesting that unnecessary human mobility is undesirable for the environment. Keywords: COVID-19; human mobility; environmental impact; CO 2 emissions; ARDL 1. Introduction As the Intergovernmental Panel on Climate Change (IPCC) states in its Fifth Assess- ment Report (AR5), the causes of climate change are largely related to anthropogenic greenhouse gas emissions driven by economic growth and population increases [1]. Thus, the simplest solution to climate change is to stop or restrict human activities. However, this is unrealistic since every country wants to enjoy economic development, and wealth is often related to economic growth. However, the recent spread of the COVID-19 has forced many countries into lockdown and, for the first time after the industrial revolution, almost the entire world is confining people at their homes, restricting human mobility. The lockdown regulations in many countries are prohibiting people from going out of their homes unless they need to buy necessities at grocery and pharmacy stores. Even going to public parks was restricted in some countries where social distancing was difficult to implement. As human mobility declined during the COVID-19 pandemic, nature is regenerating [2], and this stagnant mobility is likely reducing global greenhouse gas emissions. For example, the global CO 2 emissions are claimed to have decreased by 17% during the first quarter of 2020 relative to the mean level of emissions in 2019 [3]. Furthermore, NASA (the National Aeronautics and Space Administration) and ESA (the European Space Agency) reports that during the COVID-19 pandemic, NO 2 emissions decreased by up to 30% due to the lockdown restrictions [4]. Sustainability 2021, 13, 8534. https://doi.org/10.3390/su13158534 https://www.mdpi.com/journal/sustainability