4 min readFeb 7, 2025 05:10 PM IST
First published on: Feb 6, 2025 at 03:35 PM IST
Written by Dr Rommel Tickoo
Many people asked me if tech millionaire and longevity crusader Bryan Johnson had been biased or not about India while abruptly leaving Zerodha co-founder Nikhil Kamath’s podcast midway, citing poor air quality in the room as the reason. According to Johnson, the room’s air quality index (AQI) was 130 (ideally should be 50), with PM2.5 levels at 75 µg/m³ (ideally should be 5 to 15 µg/m³) — roughly equivalent to smoking 3.4 cigarettes a day.
“Air pollution has been so normalised in India that no one even notices anymore despite the science of its negative effects being well known… No one wore a mask which can significantly decrease exposure,” he added.
Now, whatever may be his personal reaction, fact of the matter is he has raised an issue which we should take up seriously and build awareness around. Most of us in cities like Delhi consider AQI above 100 as normal. But it is hardly that.
WHAT DOES AQI OVER 100 MEAN FOR YOU?
The normal AQI for a human body is 50. Any reading between 50 and 100 affects unusually sensitive people, like infants, the elderly, the immune-compromised and those already with severe chronic conditions like asthma. While these groups should avoid prolonged exposure, for everybody else this range makes for a good day.
When the AQI is above 100, it can affect sensitive groups like children, older adults, and people with pre-existing lung or heart conditions. These include symptoms like irritation to the eyes, nose, throat, coughing, wheezing and chest discomfort.
As the AQI increases further, even healthy individuals can experience these effects and complain of further symptoms like shortness of breath, irritation in the eyes, and chest tightness. Other than the groups mentioned above, an AQI between 101 to 150 is a red flag for children, teenagers, and pregnant women. This is the range when they should avoid prolonged exposure to the outdoors or exertion, take up less intense activity, or take more breaks from it if they cannot avoid it, and watch for coughing or shortness of breath. Asthmatics must keep nebulisers and inhalers handy in such circumstances.
Needless to say that AQI readings between 151 and 200 can be dangerous for everyone. Any readings between 201 and 300 should be considered an emergency when people should just reschedule their activity indoors or to a time when the pollution load is less. Levels between 300 and 500 are considered hazardous for the human body.
HOW PM 2.5 LEVELS AFFECT YOUR HEALTH?
Now AQI is the collective measure of all kinds of pollutants, be it ozone, particulate matter (PM2.5, PM 10), sulphur dioxide and carbon dioxide. But in our cities we have higher concentrations of PM 2.5, which is usually found in smog and industrial emissions.
Due to its tiny size, PM2.5 can easily enter the bloodstream. It has a large surface area and can carry toxins through breath, reaching the end of the respiratory tract, penetrating deep into the lungs and corroding their walls where air exchange happens. The air sacs fill up with inhaled air and the oxygen from it passes into the blood. Now PM 2.5 also gets absorbed simultaneously and further damages cell walls, triggering inflammation. And this we know is associated with heart attacks as plaques get dislodged from weakened walls.
In children, PM 2.5 can impair lung function as their lungs are still developing. There is a growing body of evidence linking long-term PM 2.5 exposure to an increased risk of lung cancer as it can change the DNA of cells and the way they divide.
PREVENTION MODE ALWAYS
Given that pollution has also moved indoors, just ventilating by letting fresh air in isn’t helping us anymore. To reduce PM2.5 in your home, use high efficiency air filters, and keep windows closed when AQI levels and pollen levels are high. Keep your pets clean too. Wear masks outdoors. This has to be a daily drill.
(Dr Rommel Tickoo is director, internal medicine, Max Superspeciality Hospital, Saket)
According to Johnson, the room’s air quality index (AQI) was 130 (ideally should be 50), with PM2.5 levels at 75 µg/m³ (ideally should be 5 to 15 µg/m³) — roughly equivalent to smoking 3.4 cigarettes a day. (Credit: Youtube/NIkhil Kamath) 
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