Air Pollution's Positive Covid-19 Impact: A Global Overview

The COVID-19 pandemic has had a significant impact on air pollution levels globally. To curb the spread of the virus, many countries implemented lockdown and social restriction measures, resulting in reduced industrial and vehicle emissions. Studies have shown that major air pollutants such as nitrogen dioxide and particulate matter pollution decreased significantly in early 2020 compared to previous years. For example, nitrogen dioxide pollution decreased by 40-60% in Chinese cities and by 20-38% in Western Europe and the US. However, the impact on air quality varied across regions, and some areas experienced an increase in secondary pollutants like ground-level ozone. Despite these improvements, air pollution remains a critical issue, with a 2025 report revealing that nearly half of Americans are exposed to unsafe levels of air pollutants.

Particulate matter pollution decreased by 35%

The COVID-19 lockdowns had a significant impact on air quality globally. Notably, particulate matter pollution decreased by 35% in northern China, according to a study published in the journal Geophysical Research Letters. This study, co-authored by atmospheric scientist Jenny Stavrakou, revealed an unprecedented drop in emissions since the 1990s when air quality monitoring from satellites began.

Particulate matter pollution, or PM pollution, refers to the presence of tiny airborne particles in the atmosphere. These particles, often originating from sources such as wildfires, wood-burning stoves, coal-fired power plants, diesel engines, and industrial emissions, pose significant health risks. Exposure to PM pollution can lead to a range of adverse health effects, including asthma attacks, heart attacks, strokes, preterm births, impaired cognitive functioning, and an increased risk of lung cancer.

The decrease in particulate matter pollution by 35% in northern China during the COVID-19 lockdowns is a significant improvement in air quality. This reduction in pollution is attributed to the decrease in human activities that typically emit large amounts of particulate matter, such as industrial operations, vehicle usage, and power generation. The lockdown measures effectively reduced the emissions from these sources, leading to improved air quality in the region.

However, it is important to note that the decrease in particulate matter pollution during the COVID-19 lockdowns may be temporary. As economic activities resume and lockdown restrictions ease, emissions from industrial operations, transportation, and other sources may increase, leading to a potential rebound in particulate matter pollution levels. Therefore, sustained efforts and policies are necessary to maintain and further improve air quality in the long term.

Nitrogen dioxide pollution decreased by 60%

The COVID-19 pandemic has disrupted social and economic activities worldwide, with many countries adopting partial or complete lockdowns. This has led to a significant reduction in air pollution levels, especially nitrogen dioxide (NO2) pollution.

Nitrogen dioxide is a primary pollutant, and its levels have been monitored using satellite sensors like the Tropospheric Monitoring Instrument (TROPOMI) and the Ozone Monitoring Instrument (OMI). Studies have found that nitrogen dioxide pollution decreased by up to 60% in some cities in northern China, such as Wuhan and Xi'an, and in other cities in Western Europe and the United States that were heavily impacted by lockdown measures. This decrease is compared to pre-pandemic levels in 2019.

In addition to northern China, cities in Western Europe and the United States also experienced a reduction in nitrogen dioxide pollution. On average, Chinese cities saw a 40% decrease, while cities in Western Europe and the United States saw a 20-38% decrease in nitrogen dioxide pollution during the 2020 lockdown compared to the same period in 2019. However, it is important to note that not all countries saw a decrease in NO2 levels. For example, Iran, one of the earliest and most severely affected countries by the pandemic, did not experience a decrease in nitrogen dioxide pollution, possibly due to a lack of strict lockdown measures in place.

The decrease in nitrogen dioxide pollution is attributed to the reduction of human activities that are major sources of pollutants. The lockdown measures during the pandemic minimized industrial activities and restricted mobility, resulting in improved air quality. This has led to a significant drop in emissions, comparable only to short-term reductions during events like the 2008 Beijing Olympics. However, it is worth mentioning that while nitrogen dioxide levels have decreased, there has been a simultaneous increase in secondary pollutants like ground-level ozone, particularly in China.

Surface ozone concentration increased by 150-200%

The COVID-19 lockdowns significantly impacted air quality globally. While the levels of major air pollutants like nitrogen dioxide and particulate matter pollution decreased drastically, the average surface ozone concentration increased by 150-200%.

Ozone is a gas composed of three oxygen atoms. It occurs naturally in small amounts in the upper atmosphere or stratosphere, where it forms a protective layer that acts as a shield against the sun's harmful ultraviolet rays. This "good" ozone is beneficial and protects living things from ultraviolet radiation.

However, ground-level or "bad" ozone is a harmful air pollutant and a secondary pollutant formed by chemical reactions between nitrogen oxide gases from vehicle and industrial emissions and volatile organic compounds (VOCs). It is the main ingredient in smog and can trigger health problems, particularly for children, the elderly, and people with lung diseases such as asthma.

The increase in surface ozone concentration during the COVID-19 lockdowns is concerning. While the decrease in primary air pollutants like nitrogen dioxide is positive, it does not necessarily lead to a decrease in ground-level ozone, as seen in China. This highlights the complexity of air pollution and the need to address multiple factors to improve air quality effectively.

The rise in surface ozone levels during the pandemic underscores the importance of continued efforts to reduce air pollution and its impact on human health and the environment. It is crucial to recognize that addressing primary pollutants alone may not be sufficient to solve the ozone problem, as stated by atmospheric scientist Guy Brasseur.

SO2, NO2, CO, and PM10 levels decreased

The COVID-19 pandemic and subsequent lockdowns have had a significant impact on air pollution levels globally. In particular, the concentrations of SO2, NO2, CO, and PM10 have decreased in many regions.

In Ji'nan, China, air quality improved significantly during the COVID-19 lockdown period. The concentration of NO2 saw the greatest reduction, decreasing by 54.02%. The smallest reduction was observed for SO2, which decreased by 27.92%. PM10 levels decreased by 44.92%, while CO levels decreased by 30.60%. These improvements in air quality are attributed to the restrictions on human movement and industrial activities during the lockdown, which resulted in a significant reduction in emissions from vehicle exhaust and industrial production.

Similar findings were observed in Salé City, Morocco, where the COVID-19 lockdown led to a reduction of more than half in PM10, NO2, and SO2 concentrations. The decrease in PM10 levels is attributed to the rapid decrease in traffic density and the decline in urban particulate emissions from local sources. The reduction in SO2 emissions is linked to the use of low-sulphur fuel and lubricant oil, as well as the closure of commercial ships and incineration activities due to pandemic control measures.

Studies have also shown that nitrogen dioxide (NO2) pollution decreased significantly in other regions during the early stages of the COVID-19 pandemic. In northern China, Western Europe, and the US, NO2 pollution decreased by up to 60% in early 2020 compared to the previous year. This decrease in air pollutants is unprecedented since air quality monitoring from satellites began in the 1990s.

While the COVID-19 pandemic and lockdowns have led to a decrease in SO2, NO2, CO, and PM10 levels in many regions, it is important to note that other pollutants, such as ground-level ozone, have increased during the same period.

Positive impacts on air quality due to LSSR

The COVID-19 pandemic has led to lockdown and social distancing measures being implemented worldwide, which have positively impacted air quality. Many cities have experienced improved air quality due to restrictions on human activities and reduced transboundary pollutants from neighbouring countries.

In South Korea, significant improvements in air quality were observed in Seoul and Daegu, with remarkable reductions in PM2.5, PM10, CO, and NO2. The effects of social distancing were maximized due to a decrease in transboundary pollutants, particularly from China, resulting in a decline in traffic-related PM2.5. Wuhan, China, where the COVID-19 outbreak began, also reported significant air quality improvements, including a 36.2% decrease in PM2.5 in January 2020 compared to previous years.

Sri Lanka, which implemented an island-wide curfew during the pandemic, saw a significant reduction in air pollutants in Colombo and Kandy. The curfew restricted transport and industrial activities, leading to a decrease in motor vehicles on the roads and resulting in a 41-51.6% reduction in PM2.5 and a 46.5-54.3% decrease in CO in Colombo. Similar findings of reduced air pollution were recorded across the South Asian region and globally.

Lockdowns in early 2020 led to a decrease of up to 60% in nitrogen dioxide pollution over northern China, Western Europe, and the US compared to the same period in 2019. Particulate matter pollution, which includes particles smaller than 2.5 microns, decreased by 35% in northern China. These significant drops in emissions are unprecedented since air quality monitoring from satellites began in the 1990s.

While the lockdown and social distancing measures have had a positive impact on air quality, it is important to note that surface ozone levels have increased in some regions, such as China and South Korea, as a secondary effect of the reduced nitrogen dioxide and particulate matter.

Frequently asked questions