SARS CoV-2, also known as Covid-19, had an outbreak in 2019 with a first case reported in Wuhan, China. The virus only hit the shores of South Africa in March 2020. Covid-19 is a respiratory illness which is caused by the Corona Virus. The illness is spread by respiratory droplets through coughing and sneezing from an infected individual (although it was recently argued that it is airborne). There have been different variants of the Corona Virus that infected humans over the years such as SARS (Severe Acute Respiratory Syndrome, 2003) and MERS (Middle East Respiratory Syndrome, 2012). While completely different, Covid-19 and air pollution both have the potential to cause mortality due to respiratory complications.

Air pollution is defined as any unwanted gases and particles suspended in the atmosphere. Common air pollutants include Nitrogen Oxides (NOx), Sulphur Dioxide (SO2), particulate matter and Carbon Dioxide (CO2). Although Covid-19 may be exacerbated by the effects of air pollutants, Covid-19 has an indirect positive impact on air pollution through reduced activities in different lockdowns implemented at different cities and countries. 

Covid-19 mortality and air pollution

It is already known that Covid-19 can be fatal to humans, however, the virus does not have a uniform health impact on all infected individuals. Air pollution is also known to cause over 4 million mortalities per annum globally. The effects of Covid-19 on individuals are exacerbated by underlying health conditions, especially respiratory health conditions that may be caused by air pollution. The link between air pollutants and Covid-19 mortalities stems from the air pollutants causing cardiopulmonary diseases, diabetes, lung cancer, pneumoconiosis, silicosis, progressive massive fibrosis (PMF), and other advanced lung diseases collectively referred to as chronic obstructive pulmonary disease (COPD) which invariably increases the potential of mortality in individuals who also contract Covid-19.

To individuals displaying underlying health conditions, contracting Covid-19 may be more serious as these conditions would generally cause the immune system to deteriorate thereby facilitating viral penetration and replication. Pollutants such as Nitrogen Dioxide (NO2) and particulate matter were noted to increase susceptibility to bacterial and viral infections. An example of a higher mortality rate experienced in individuals with chronic diseases can be found in a study by Bennett et al (2021), where higher mortalities were noted in individuals suffering from chronic diseases such as heart, neurological, respiratory, kidney, or liver diseases.

Air pollution impacts of Covid-19

Numerous studies have been carried out to determine the air pollution reductions that may have occurred as a result of lockdowns being implemented across the globe. Many of these studies attempted to assess the concentrations of pollutants pre-lockdown, as well as during lockdown, but did not take into consideration the meteorological conditions that may affect the dispersion of pollutants and other localised aspects that contribute to the concentrations found in the atmosphere.

Different studies concur that some air pollutants such as Nitrogen Dioxide (NO2), particulate matter, and Ozone, dropped in concentration levels when Covid-19 lockdowns were introduced. The reduction of air pollutants was dependant on the levels of lockdown, activities allowed as well as the localisation of activities, such as vehicle movement and coal-based electric generation, that were permitted during these lockdowns. General traffic air pollutants such as particulate matter, Nitrogen Dioxides (NOx) and Ozone showed a decrease in many studies across different cities where traffic movement was limited during the different lockdown levels in different countries as opposed to the time pre-lockdown. The reduction of other air pollutants was based on locality conditions such as the level of lockdown, activities permitted during lockdown and meteorological conditions at the time.

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Further reading:

https://doi: 10.1183/16000617.0242-2020