High PM 2.5 levels in winter, Diwali worsen Covid-19, say doctors

Exposure to fine particulate matter is also associated to cardiovascular diseases

Increased particulate matter (PM) 2.5 levels in the air can worsen Covid.

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% increase in Covid-19 death rate. Pulmonologists in the city say fine particulate matter, both indoor and outdoor, worsen Covid-19 disease outcomes.

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PM 2.5 refers to tiny particles or droplets in the air that are two-and-a-half microns or less in width. Particles in the PM 2.5 size range can travel deeply into the respiratory tract, reaching the lungs.

This is particularly important in the context of the upcoming Deepavali festival, when air gets a lot worse. Chest medicine experts say patients have to be sensitised to this.

On Thursday, Hombegowda Nagar and Jayanagar 5th Block had an Air Quality Index of 154 and 152 at noon, which is ‘unhealthy’. Particulate matter can cause inflammation in the lungs and an inflamed lung infected with SARS-CoV-2 virus will lead to a worse outcome.

Dr Murali Mohan, pulmonologist, Narayana Health, said, “The more particles remain suspended in the air the longer the virus will remain suspended in the air and transmission is likely to be higher. When the particles do get inhaled, it will lead to more severe inflammatory reaction. These are the two main reasons why there’s an association between air pollution and complications, including mortality, in Covid-19.”

Exposure to fine particulate matter is also associated with cardiovascular diseases. Dr H Paramesh, paediatric pulmonologist, environmentalist and professor at Divecha Centre for Climate Change, Indian Institute of Science, told DH, “PM 2.5 penetrates the lung parenchyma (substance of the lung outside of the circulatory system that is involved with gas exchange). Some of them cross over and reach the blood vessels causing clotting in the blood vessels. This worsens Covid.”

Dr C Nagaraj, director, Rajiv Gandhi Institute of Chest Diseases, said, “Healthy individuals are more likely to get respiratory infections, including Covid, when fine dust particles are more in the air. Those suffering from chronic obstructive pulmonary diseases and asthma patients are more susceptible to Covid. Especially, during winter and Deepavali, we advise them to stay at home because this exaggerates the disease process. There’s a definite correlation between contracting Covid early and PM 2.5.”

Dr Satyanarayana Mysore, pulmonologist, Manipal Hospital, said, “The US Harvard study is a mathematical model and has used historical data. It is not a direct outcome study. A similar study was done in northern Italy. It is known that whenever PM 2.5 levels are more, hospital admissions for respiratory diseases are more. Covid symptoms can be severe when the lung is already inflamed. But there’s no harm in taking precautions as pre-Deepavali PM 2.5 levels drastically rise post-Deepavali.”