New Delhi, Jul 2: People living in the national capital and in states such as Maharashtra, Uttar Pradesh, Madhya Pradesh and Tamil Nadu are more likely to contract COVID-19 due to prolonged exposure to high concentration of PM 2.5, according to a new pan-India study.

Sixteen major cities, including Delhi, Mumbai, Chennai, Bangalore, Kolkata, Pune, Ahmedabad, Varanasi, Lucknow and Surat, reported the highest number of COVID-19 cases, and PM2.5 emissions are also higher in these areas due to fossil fuel-based anthropogenic activities, it said. Delta and Delta Plus Variants FAQs: Is New Variant Deadlier? Know Everything About Coronavirus Mutation, Symptoms and Efficacy of COVID-19 Vaccines.

PM2.5 refers to fine particles which penetrate deep into the body and fuel inflammation in the lungs and respiratory tract, leading to the risk of having cardiovascular and respiratory problems, including a weak immune system.

The study conducted in 721 districts across India establishes a strong relationship between the PM2.5 emission load and COVID-19 infections and resulting deaths, according to one of the authors, Gufran Beig, who is the director of the System of Air Quality and Weather Forecasting and Research (SAFAR).

Researchers from Utkal University, Bhubaneswar; Indian Institute of Tropical Meteorology, Pune; National Institute of Technology, Rourkela and IIT-Bhubaneswar studied data related to emissions, air quality and COVID-19 cases and deaths in these districts till November 5 last year.

This study provides the first practical evidence for India that “cities having pollution hotspots where fossil fuel emissions are dominating are highly susceptible to COVID-19 cases”, the findings read.

The study has been named 'Establishing a link between fine particulate matter (PM2.5) zones and COVID -19 over India based on anthropogenic emission sources and air quality data'.

Higher numbers of COVID-19 cases have been found in Delhi and states such as Maharashtra, Rajasthan, Tamil Nadu, Uttar Pradesh, Andhra Pradesh, Telangana, Gujarat, Bihar, Karnataka, Odisha and Madhya Pradesh with prolonged exposure to the high concentration of PM2.5, the report said.

If the trend of good correlation coefficient persists then communities living in these areas are more likely to get affected by COVID-19, according to the study.

According to the study, bad air quality days have a visible relationship with the number of COVID-19 casualties.

"There's an exponential increase in the number of casualties once the bad air quality days cross the value of 100," it said.

Delhi, which witnesses 288 bad air quality days per year on an average, reported 4,38,529 coronavirus cases and 6,989 deaths due to the disease till November 5 last year.

Mumbai, which records 165 bad air quality days a year on an average, reported 2,64,545 cases and 10,445 deaths during the period. Pune, which records 117 bad air quality index days a year, reported 3,38,583 cases and 7,060 fatalities.

However, there are some anomalies – Srinagar that records 145 bad air days a year had 20,413 cases and 375 fatalities till November 5, while Bengaluru, which witnesses just 39 bad air quality days in a year, reported 3,65,959 cases and 4,086 deaths.

"The study shows the correlation coefficient between PM2.5 emission load and COVID-19 cases is high but not 100 per cent. In such a case, there will be some anomalies which could be attributed to several confounding factors, including the number of tests," Beig explained.

The researchers also said that residential emissions from biofuel burning (emissions from cooking, heating etc) "emerged as a crucial sector in elevating PM2.5 load over the country even during the lockdown situations and correlating with COVID-19 cases rise".