Higher air pollution could increase Covid death rate
Two studies make links with virus; connection could have implications for India
NEWDELHI: Air pollution is likely to be a major risk factor in coronavirus disease (Covid-19) mortality, scientists have contended -- a finding that could have serious implications for India.
Prolonged exposure to air pollution leads to a chronic inflammatory response even among the young and healthy, which makes people living in polluted areas more susceptible to developing chronic respiratory conditions. This is borne out by the high Covid-19-related death rates in northern Italy compared to the rest of the country, according to environmental scientists and physicians in Italy.
And an analysis by Harvard University’s TH Chan School of Public Health, published in MedRxiv, a pre-print journal for health sciences, on April 5, of 3,080 counties in the US, an increase of only 1 microgram per cubic metre in PM 2.5 (particulate matter with a diameter measuring 2.5 micrometres or less) concentrations is associated with a 15% increase in Covid-19 deaths.
The US’s annual PM 2.5 average is around 9.9 micrograms per cubic metre (meets the World Health Organization’s annual air quality guideline of 10 micrograms per cubic metre) whereas India’s annual average PM 2.5 concentration was more than 80 micrograms per cubic metres in 2017, according to an Indian Council of Medical Research (ICMR) study, indicating that Indians’ exposure to polluted air is about eight times higher.
“Their analysis is robust.We need to estimate the same for India as it is not possible to extrapolate the impact at high pollution level linearly. Covid mortality rate also depends on pre-existing conditions (like diabetes, heart problems). So, the Indian context may be completely different. As of now we may not have enough Covid cases to perform the analysis and get the statistically significant result,” said Sagnik Dey, associate professor at the Centre for Atmospheric Sciences, Indian Institute of Technology-Delhi.
In another paper titled “Can atmospheric pollution be considered a co-factor in extremely high-level of Sars-CoV-2 lethality in Northern Italy?” published in Elsevier’s journal of Environmental Pollution on April 4, scientists said that the mortality was 12% in Lombardy and Emilia Romagna, compared to 4.5% in the rest of the country. This region is one of Europe’s most polluted based on data from the Ozone Monitoring Instrument on the National Aeronautics and Space Administration (Nasa)’s Aura satellite.
The data indicates that there is stagnation of pollutants in the region because of geographical and climatic factors. A review of the air quality index , based on the concentrations of particulate matter and other gases, is also the worst in this region in Italy.
“Air pollution represents one of the most well-known causes of prolonged inflammation, eventually leading to an innate immune system hyper-activation,” the study by scientists at the rheumatology unit of the University of Siena and departmental of environmental science at Arhaus University said.
The paper concluded that pollution impairs the first line of defence of the upper airways called cilia (microscopic hair-like structures or organelles) which is why people in polluted areas are more likely to develop chronic respiratory conditions due to an infective agent like Sars-CoV-2.
This was seen during the severe acute respiratory syndrome (Sars) outbreak in 2002 too. A study by scientists of the Fielding School of Public Health analysed five regions with 100 or more Sars cases which showed that the fatality rate increased with the increment in AQI or air pollution levels. Moderate AQIs had an 84% increased risk of dying from Sars compared to those from regions with lower AQI.
“When a population is chronically exposed to high levels of air pollution, the lung is compromised. The lung develops an inflammation. In short, the lung becomes ready for external attack. Those living in areas with cleaner air are more battleready,” said Dr Manas Ranjan Ray, former assistant director of Kolkata-based Chittaranjan National Cancer Institute.
“There have bee high cases of chronic obstructive pulmonary disorder (COPD), rhinitis and other conditions, which have manifestations similar to Covid-19. Indian population is extremely vulnerable to rhinoviruses but we’ve grown immunity and come out of it within four to five days. But the unique feature of Sars-CoV-2 is that it can be fatal for some people. This is a great opportunity to study how the impact of a new virus is influenced by air pollution,” he added.
› Indian population is extremely vulnerable to rhinoviruses but we’ve grown immunity and come out of it within four to five days. But Sars-CoV-2 can be fatal for some people DR MANAS RANJAN RAY, former assistant director Chittaranjan National Cancer Institute