New Delhi (NVI): As coronavirus global death toll has passed half a million mark, one of the major factor that could partially explain this is air pollution, according to a new study.
The study shows a correlation between the level of air pollution and the number of COVID-19 cases. It shows the relationship between COVID-19 cases and exposure to air pollution in the Netherlands which found that the equivalent figure for that country could be up to 16.6 per cent.
According to the research, the long term exposure to pollutants such as fine particulate matter (often called PM2.5, as these are particles smaller than 2.5 micrometres), nitrogen dioxide (NO₂) and sulphur dioxide (SO₂) can reduce lung function and cause respiratory illness.
These pollutants have also been shown to cause a persistent inflammatory response even in relatively younger people and to increase the risk of infection by viruses which targets the respiratory tract.
Moreover, the pathogen that causes COVID-19 – SARS-CoV-2 – is one such virus.
Meanwhile, several other studies have already suggested that poor air quality can leave people at greater risk of contracting the virus, and at far more greater risks of serious illness and death.
Another study of the US found that even a small increase in PM2.5 concentrations of 1 microgram per cubic metre is associated with an 8 per cent increase in the COVID-19 death rate.
This study, analysed the data for 355 Dutch municipalities, and found that an increase in fine particulate matter concentrations of 1 microgram per cubic metre was linked with an increase of up to 15 COVID-19 cases, four hospital admissions and three deaths.
The first confirmed COVID-19 case in the Netherlands occurred in late February and by late June over 50,000 cases had been identified. Notably, these hotspots of disease transmission are in relatively rural regions where there are fewer people living close together.
In late February and early March each year, these areas hold carnival celebrations which attract thousands of people to street parties and parades.
While it’s likely that the carnival celebrations played a role, the pattern of cases across these regions suggest other factors may be as important.
The south-eastern provinces of North Brabant and Limburg house over 63 per cent of the country’s 12 million pigs and 42 per cent of its 101 million chickens. Intensive livestock production produces large amounts of ammonia.
These particles often form a significant proportion of fine particulate matter in air pollution. Concentrations of this are at their highest in air samples from the south-east of the Netherlands.
According to the analysed data that has used COVID-19 cases up to June 5, 2020, capturing almost the entire known course of the Dutch epidemic, the relationship found between pollution and COVID-19 exists even after controlling other contributing factors, such as the carnival, age, health, income, population density and others.
Furthermore, the highest annual average concentration of fine particulate matter in a Dutch municipality is 12.3 micrograms per cubic metre, while the lowest is 6.9, as per the study.
If concentrations in the most polluted municipality fell to the level of the least polluted, the results suggest this would lead to 82 fewer disease cases, 24 fewer hospital admissions and 19 fewer deaths, purely as a result of the change in pollution.
The correlation found between exposure to air pollution and COVID-19 is not simply a result of disease cases being clustered in large cities where pollution may be higher. After all, COVID-19 hotspots in the Netherlands were in relatively rural regions.
So far, within regions, pollution levels and COVID-19 cases vary considerably from place to place, making it hard to estimate the precise relationship between the two.
However, until this kind of data is available, the evidence of a relationship between pollution and COVID-19 can never be conclusive.