The COVID-19 pandemic has had an impact on the environment, with changes in human activity leading to temporary changes in air pollution, greenhouse gas emissions and water quality. As the pandemic became a global health crisis in early 2020, various national responses including lockdowns and travel restrictions caused substantial disruption to society, travel, energy usage and economic activity, sometimes referred to as the "anthropause". As public health measures were lifted later in the pandemic, its impact has sometimes been discussed in terms of effects on implementing renewable energy transition and climate change mitigation.

With the onset of the pandemic, some positive effects on the environment as a result of human inactivity were observed. In 2020, carbon dioxide emissions fell by 6.4% or 2.3 billion tonnes globally. In April 2020, emissions fell by up to 30%. In China, lockdowns and other measures resulted in a 26% decrease in coal consumption, and a 50% reduction in nitrogen oxide emissions. Greenhouse gas emissions rebounded later in the pandemic as many countries began lifting restrictions, with the direct impact of pandemic policies having a negligible long-term impact on climate change.

Some developed nations introduced so-called "green recovery" economic stimulus packages, aiming to boost economic growth while facilitating renewable energy transition. One of these investments was the European Union's seven-year €1 trillion budget proposal and €750 billion recovery plan, "Next Generation EU", which seeks to reserve 25% of EU spending for climate-friendly expenditure.

However, decreased human activity during the pandemic diverted attention from ongoing activities such as accelerated deforestation of the Amazon rainforest and increased poaching in parts of Africa. The hindrance of environmental policy efforts, combined with economic slowdown may have contributed to slowed investment in green energy technologies.

The pandemic also led to increased medical waste. Production and use of medical equipment such as personal protective equipment (PPE) contributed to plastic waste. The medical response required a larger than normal number of masks, gloves, needles, syringes, and medications. During 2020, approximately 65 billion gloves and 129 billion face masks were used every month, and were disposed of. Enforced public use of PPE has posed challenges to conventional waste management. Greenhouse gas emissions resulting from the treatment process of this plastic waste ranged from 14 to 33.5 tons of CO2 per ton of mask, the largest share being from production and transport.

Background

Environmental issues Increasing amounts of greenhouse gases since the beginning of the industrialization era has caused average global temperatures on the Earth to rise. Climate change has led to the melting of glaciers, an increase in extreme weather, loss of species, frequent wildfires, and rising sea levels. Prior to the COVID-19 pandemic, measures that were expected to be recommended by health authorities in the case of a pandemic included quarantines and social distancing. Simultaneously, a research paper published in 2018 predicted that a reduction in economic activity would target the issues created by global warming; it would halt rising temperatures, as well as diminish air and marine pollution, and benefit the environment. The relationship between human activity and the environment had been observed in various public health crises in the past, such as during the Spanish flu and smallpox epidemics, and was observed again with the COVID-19 pandemic.

COVID-19 pandemic On 11 March 2020, the outbreak of COVID-19 was declared a pandemic by the World Health Organization (WHO). By 5 July 2020, 188 countries or regions had reported cases of COVID-19. As of November 2021, the continuing COVID-19 pandemic had killed over 5 million people. As a result of the severity of the virus, most countries enacted lockdowns to protect people, mitigate the spread of the virus, and ensure space in hospitals. These lockdowns disrupted daily life worldwide, decreasing the level and frequency of human activity and production.

COVID-19 forced industries, businesses, and large corporations to shut down. Although the damage caused to human life, the economy, and society was extensive, the dramatic changes to human activity had an impact on the environment. Surplus to emerging estimates of monthly energy supply or estimated parameters that constructed the near-real-time daily CO2 emission inventories during COVID reduction was observed based on activity from power generation (for 29 countries), industry (for 73 countries), road transportation (for 406 cities), aviation and maritime transportation and commercial and residential sectors emissions (for 206 countries). This decline in CO2 emissions was followed by decline in regional concentrations of nitrogen oxide, which was observed by ground-based networks and satellites. These emissions were calculated by researchers in which observations showed little impact (less than 0.13ppm by 30 April 2020) on the over-served global concentration.

Reductions in fossil fuel consumption as well as economic activity due to travel restrictions, business closures and other dramatic responses due to COVID-19 were recorded. As human activity slowed globally, a substantial decrease in fossil fuel use, resource consumption, and waste disposal was observed, generating less air and water pollution in many regions of the world. Specifically, there was a sharp and lasting decline in planned air travel and vehicle transportation throughout the COVID-19 pandemic, which in effect reduced the net carbon emission across the globe.

With the impact being noted, some researchers and officials called for biodiversity and environmental protections as part of COVID-19 recovery strategies.

Air quality

Due to the pandemic's impact on travel and industry, the planet as a whole experienced a decrease in air pollution. A reduction in air pollution mitigated both climate change and COVID-19 risks, but it has not yet been established which types of air pollution, if any, are common risks to both. The Centre for Research on Energy and Clean Air reported that methods to contain the spread of SARS-CoV-2, such as quarantines and travel bans, resulted in a 25% reduction of carbon emission in China. In the first month of lockdowns, China produced approximately 200 million fewer metric tons of carbon dioxide than of the same period in 2019 due to a reduction in air traffic, oil refining, and coal consumption. In this same period, car travel fell by 70% in the UK. One Earth systems scientist estimated that this reduction may have saved at least 77,000 lives. However, Sarah Ladislaw from the Center for Strategic & International Studies argued that reductions in emissions resulting from economic downturns should not be viewed as beneficial, because China's return to previous rates of growth amidst trade wars and supply chain disruptions in the energy market will worsen its environmental impact. Additionally, Nature reported that in 2020, global carbon emissions only fell by 6.4%.

Between 1 January and 11 March 2020, the European Space Agency observed a marked decline in nitrous oxide emissions from cars, power plants, and factories in the Po Valley region in northern Italy, coinciding with lockdowns in the region. Throughout areas in North India such as Jalandhar, the Himalayas became visible again for the first time in decades, as the drop in pollution triggered air quality improvement.

During the initial phase of the COVID-19 pandemic, NASA and the ESA monitored the significant decrease in nitrogen dioxide gases in China. The economic slowdown from the virus drastically reduced pollution levels, especially in cities like Wuhan, China by 25-40%. NASA used an ozone monitoring instrument (OMI) to analyze and observe the ozone layer as well as pollutants such as NO2, aerosols, and other chemicals. This instrument helped NASA to process and interpret the data coming in due to the lock-downs worldwide. According to NASA scientists, the drop in NO2 pollution began in Wuhan, China and slowly spread to the rest of the world. The drop occurred drastically because the emergence of the virus coincided with the same time of year as the Lunar Year celebrations in China. During this festival, factories and businesses were closed for the last week of January to celebrate the Lunar Year festival. The drop in NO2 in China did not achieve an air quality of the standard considered acceptable by health authorities. Other pollutants in the air such as aerosol emissions remained.

In early 2020, improvements were observed in transboundary Southeast Asian haze, attributed to lockdowns and other restrictions introduced by governments, as well as favourable meteorological conditions.

Joint research led by scientists from China and the U.S. estimated that nitrogen oxide emissions decreased by 50% in East China from 23 January (Wuhan lockdown) to 9 February 2020 in comparison to the period from 1 to 22 January 2020. Emissions then increased by 26% from 10 February (back-to-work day) to 12 March 2020, indicating possible increasing socioeconomic activities after most provinces allowed businesses to open. It is yet to be investigated what COVID-19 control measures are most efficient controlling virus spread and least socioeconomic impact.

According to the World Health Organization, more than 80% of individuals living in cities are typically exposed to dangerous air pollution, which has been associated with an increased risk of COVID-19 problems and mortality.

The changes in air pollution during COVID lockdowns have also impacted water quality. Scientists have long noted that air quality and surface water quality have a close connection; however, the decrease in air pollution during the pandemic specific impact on water systems remains unclear. Most studies have found that improvements due to COVID-19 were temporary, although there have been notable decreases in pollutants in various water systems.

India On 30 January 2020, the first COVID-19 case in India was recorded in Kerala in South India, which was followed by a nationwide lockdown from 25 March to 31 May 2020. Reduction in air pollution as well as improvement in air quality was reported due to the lockdown which came as a relief to the environment; restrictions on industrial activities were also beneficial. Many Indian cities also observed a major reduction in air pollution. Even the industrial state of Gujarat, situated on the west coast of India, reported remarkable reduction of air pollutants due to restrictions imposed on industrial activities and traffic between the lockdown period from 25 March to 20 April 2020. Some of the major air pollutants, like nitrogen dioxide and sulphur dioxide, decreased by one to two per cent along with average reduction of 0.3 degree Celsius in temperature in Vapi within the year 2019. Moreover, the emissions of pollutants decreased on an average of fifty-one to seventy two per cent, resulting in an average temperature dropdown by two degrees Celsius within the lockdown period. Megacities Mumbai, Delhi, Chennai and Kolkata also reported the fall in temperature in Celsius by 2°, 3°, 2° and 2.5° respectively. The COVID-19 lockdown led to improvement of the water and air quality due to significant fall of air pollutants as reported in countrywide researches. Emissions of chemicals which lead to pollution of the environment such as carbon monoxide, ammonia, sulphur dioxide and nitrogen dioxide showed a significant reduction of 22.82%, 30.61%, 32.11% and 46.95% respectively; PM2.5 as well as PM10 reported a downfall by 57.09% and 48.56% respectively, resulting in improvement of air quality during the fourth phase of lockdown, from 22 March to 31 May 2020, named "Janta Curfew".

Water quality