Covid-19 fourth wave scare: Is Delhi's deteriorating air quality causing surge in coronavirus cases?

Delhi on Tuesday recorded over 1,000 new Covid-19 cases in a single day for the fifth consecutive day.

REPRESENTATIONAL IMAGE (CREDITS: REUTERS)

New Delhi: The national capital on Tuesday (April 26, 2022) recorded over 1,000 fresh Covid-19 cases in a single day for the fifth consecutive day. Delhi saw 1,204 new coronavirus infections and one fatality, while the positivity rate stood at 4.64 percent, according to data shared by the health department on Tuesday.

The capital had on Monday reported 1,011 cases, while the positivity rate rose to 6.42 percent. Delhi on Sunday had seen 1,083 Covid-19 cases with a positivity rate of 4.48 per cent, while on Saturday, the city had registered 1,094 coronavirus infections, the highest since February 10, with a positivity rate of 4.82 per cent.

On Friday, Delhi had logged 1,042 cases with a positivity rate of 4.64 per cent. 

The number of active cases in the city has now increased to 4,508 on April 26 from 601 on April 11, according to health department data. The infection tally in the national capital stands at 18,77,091 and the death toll at 26,169.

According to a new study, Delhi's increased pollution level may be the cause behind the sudden spike in Covid-19 cases in the capital. It is noteworthy that Delhi's average Air Quality Index (AQI) in April has so far been 19 per cent more than in March and 11 per cent more than in February.

The study, published in JAMA Network Open, claims that exposure to certain traffic-related air pollutants is associated with a greater likelihood of testing positive for the SARS-CoV-2 virus. It showed associations between infection risk and exposure to particles with a diameter less than 10 micrometers (PM10) and 2.5 micrometers (PM2.5), two days before a positive test and exposure to black carbon one day before.

The researchers, however, found no link between the risk of infection and nitrogen oxides.

"Our results add to the growing body of evidence that air pollution has a part to play in Covid-19 and support the potential benefit of improving air quality," said Olena Gruzieva, Associate Professor at the Institute of Environmental Medicine at Karolinska Institutet in Sweden.

Since pollutants in outdoor air can increase the risk of respiratory infections such as influenza and SARS, the Covid-19 pandemic aroused fears that they could also contribute to the risk of SARS-CoV-2 infection. Studies have also shown that areas of poor air quality have more cases of Covid-19.

Researchers at Karolinska studied this more closely by examining the link between estimated exposure to air pollutants at home addresses and positive PCR tests for SARS-CoV-2 in young adults in Stockholm, Sweden.

The researchers identified 425 individuals who had tested positive for SARS-CoV-2 (PCR test) between May 2020 and the end of March 2021. They note that the results might be affected by the willingness to take a PCR test and the fact that many of the young adults were asymptomatic or had only mild symptoms following infection.

It is pertinent to note that on February 24, the daily infection rate of Covid-19 in Delhi was around 1 per cent. It then stayed below 1 per cent for 38 days and crossed 1 per cent after 38 days on April 4. 

On the other hand, the average AQI of Delhi in the month of February was 225. In March, the average AQI of the capital decreased by 7 per cent as compared to February and stood at 210.

Now in April, the average AQI has touched 251, around 19 per cent higher than March and 11 per cent higher than February.

(With agency inputs)