Air pollution likely to hinder India's fight against COVID-19: Scientists

New Delhi: The causal link between air pollution and COVID-19 cases is yet to be established conclusively but long-term exposure will certainly make people more vulnerable to lung infections, warn scientists as the skies over large parts of north India, including Delhi, turn smoky and the air quality deteriorates rapidly.

Their concerns come amid several global studies pointing to the possible connection between higher air pollution levels and increased COVID-19 cases and deaths.

A study by researchers at Harvard University in the US in September showed that an increase of only one microgram per cubic metre in PM 2.5 is associated with an 8 per cent increase in the COVID-19 death rate.

Given the current limited literature, the surge of PM2.5 level in Delhi may be associated with increased COVID-19 cases... Although the literature is relatively sparse at this stage, Xiao Wu, corresponding author of the Harvard study, said.

He said the relationship between long-term air pollution and COVID-19 has been documented in many studies, which indicate that adverse health impacts of air pollution can make people prone to the infection or exacerbate the severity of COVID-19 symptoms once infected.

This is interesting, especially considering COVID-19 causes viral pneumonia and acute respiratory distress syndrome, and severe inflammation to the heart and circulatory system, the scientist said.

Another study by the University of Cambridge in April found an association between living in an area of England with high levels of air pollution and the severity of COVID-19, caused by the SARS-CoV-2 virus. Based on our findings, I would expect to see an association between higher levels of air pollution in India and COVID-19 in the winter, similar with what we found in England, said Marco Travaglio, corresponding author of the Cambridge study.

If the levels of air pollution have been consistently above the legal limits for several months or years before this coming winter, I would expect to see a relationship between those levels and COVID-19 burden across different parts of India in November and thereafter, Travaglio said.

He noted that a key component of PM2.5 toxicity is its composition which may vary considerably between countries.

Nonetheless, the WHO legal limits for PM2.5 are currently set at 10 g/m (microgrammes per cubic metre) annual mean. Levels beyond 500 g/m are extremely high and may have considerable impact on people's health in relation to COVID-19 but also beyond it, said Travalgo.

The level of small particulate matter (PM2.5) levels in Delhi have averaged around 180-340 g/m in the past few weeks while that of bigger pollution particles (PM10) has hovered between 120 and 450 during the time.

Long-term exposure to chronically high PM2.5 levels weakens the ability of the lungs to fend off infections, therefore making people more susceptible to COVID-19, the scientists said.

In addition, studies from Italy have shown that traces of SARS-CoV-2 RNA, the genetic material of the virus, can be found on pollution particles, meaning that increased air pollution may act as a vehicle to increase COVID-19 transmission in highly polluted places.

The air quality in north India is expected to deteriorate further from November to February due to several factors such as stubble burning, festive fireworks and low wind speed conditions which lead to an uptick in vehicular and industrial pollution being trapped in the lower atmosphere.

"In view of this evidence, high levels of PM2.5 in Delhi may lead to a higher number of COVID-19 cases, Travalgo added.

Studies in humans have shown that toxic air particles can penetrate airways and cause widespread infiltration of lung cells.

This chronic state of inflammation may induce or aggravate health conditions such as asthma, chronic obstructive pulmonary disease, cardiovascular diseases and diabetes, experts said.

Because these conditions have been widely found to be associated with increased risk of contracting COVID-19 or incurring into critical illness, it is likely that air pollution acts as a risk factor to increase the susceptibility to COVID-19.

India has the world's second-highest caseload of over 7.9 million and the third-highest death toll with more than 115,000 from the novel Coronavirus.

In the steepest weekly fall yet in COVID-19 numbers in India, fresh infections recorded this week (October 19-25) were nearly 16 per cent less than the previous week's tally while deaths from the virus fell by 19 per cent during this period.

India recorded just over 3.6 lakh fresh cases during the week, the lowest in absolute terms in three months (since 3.2 lakh were detected in the July 20-26 week), as per data collated from state governments.

This marked a drop of 15.7 per cent from the previous week's numbers, the sharpest weekly fall in cases since the pandemic hit India. Last week, nearly 4.3 lakh cases were recorded in the country.

This was the sixth straight week of decline in fresh Covid-19 cases from the peak of 6,45,014 infections reported during September 7-13, indicating a sustained reduction in the pandemic's spread in India.

Meanwhile, new Coronavirus infections reported in India in a span of 24 hours dropped below 50,000 for the second time this month, while the new fatalities registered during the same period fell under 500 after 108 days on Monday.

India's COVID-19 caseload mounted to 79,09,959 with 45,148 new infections being reported in a day. The death toll climbed to 1,19,014 with 480 new fatalities.

A total of 71,37,228 people have recuperated from COVID-19 so far pushing the national recovery rate to 90.23 per cent, while the case fatality rate has dropped to 1.50 per cent.

The National Centre for Disease Control (NCDC) has warned that Delhi is likely to report around 15,000 COVID-19 cases daily in winter because of the prevalence of respiratory illnesses during this season that worsen the symptoms of the disease. On Sunday, the national capital recorded 4,136 fresh COVID-19 cases, the highest single-day spike in 38 days.

PM2.5 are finer particles which remain suspended in the air for a long time and hence droplet or viral particles can cling on to these particles to increase the risk. They may increase the number of cases as pollution increases especially with large PM2.5 levels," Bhardwaj, associate professor at the Indian Institute of Technology-Bombay, said.

He said the government should make contingent plans to deal with an expected large number of cases and warned that any healthcare system can be overwhelmed by a larger number of cases.

With Agency Inputs