The surge in the Covid-19 cases in Delhi towards the end of last year could have been caused by the pollution caused by stubble burning, a research paper has suggested. According to a research paper published by researchers at the Indian Institute of Tropical Meteorology (IITM) in Pune, it has been concluded that the pollutants present in the air caused by the stubble burning increase the spread and infection rate of Covid-19 in multiple ways, and the surge in October and November in 2020 has been attributed to the same.
Indian Institute of Tropical Meteorology is an autonomous institution under the Ministry of Earth Sciences of the Government of India. It is tasked with research in monsoon, weather systems and climate-related processes in the tropical region.
The peer-reviewed paper authored by Aditi Rathod and Gufran Beig says that the Covid-19 numbers in Delhi were declining in the second half of last year, but it suddenly started to rise in October, which coincided with the burning of stubble by the farmers mostly in neighbouring Punjab and Haryana. The researchers wanted to find out if there is any direct correlation between the level of particulate pollutants, mainly Black Carbon (BC), in the air with the spread of microbes that cause various diseases including Covid-19. Most of the Black Carbon in the air comes from the burning of biomass like crop stubble, and it is the main component of soot.
The study was conducted using pollution data for Delhi from September to December, 2020, and analysing the same with the daily Covid-19 numbers for the city in that period.
The researchers have arrived at shocking conclusions after the study, which shows that the stubble burning contributed heavily to the rising cases of Covid-19, which happened in multiple ways. The stubble burning produces black carbon, which gets ‘aged’ as it travels towards Delhi. During its ageing process, it gets combined with other pollutants, which increases its size. The aerosolised virus gets attached to these particles, piggybacks on them to remain suspended in air and also to spread to wider areas. As the number and size of such BC particles increase in the air, the number of viruses on them also increases. Such viruses attached to black carbon particles have been called carbonised virus.
The pollution also increases the level of nitrates and sulphates in the atmosphere, and they help the SARS-CoV-2 virus to reproduce at a faster rate. Thus, the polluted air provides the Covid-19 virus an ideal scenario to multiply and spread at a faster rate.
When people inhale these Black Carbon particles, the virus particle also goes deep down into the respiratory system, thereby increasing the total dose delivered and total duration for which the virus stays there.
The soot caused by stubble burning also causes inflammation of the lungs, which can cause asthma and other respiratory diseases. This causes serious damage to the functions of the lungs. When such an already compromised lung is infected with the Covid-19 virus carried by the Black Carbon particles, it becomes a double whammy for the lungs and increases the complications of the Covid-19 infection.
The research found that BC concentration directly corresponds to the speed of the spread of the Novel Coronavirus at the onset of winter and stubble burning period. Moreover, the infections came down gradually after December in Delhi, when the stubble burning in the farms had declined. The study also found direct correlation of total PM2.5 level in the air with Covid-19 numbers and the deaths caused by Covid-19.
Intestinally, the PM2.5 level in the air remained high even after stubble burning had ended, but this didn’t cause an increase in Covid-19 infections. This shows that the black carbon particles that originated from stubble burning are specifically responsible for the spread of the virus, and the same particles coming from other sources may not be that responsible.
Based on this analysis of data, the study concluded that SARS-CoV-2 has the potential to be transmitted aggressively through an aged Black carbon-rich environment with fire’s microbial content rather than any particulate pollution.
Although the researchers have not tested the infectivity of the carbonised virus clinically, they have proposed that SARS-CoV-2 may have the potential to be more lethal when piggybacking on aged black carbon as the black carbon particles themselves cause serious damaging effects to lungs. As a result, the study points out that atmospheric and public health sciences need to expand their perspectives to include the potential impact of smoke’s black carbon and microbial cargo on human populations.