What number makes you feel like the air quality is improving – AQI 150? 100? Maybe 80? Many of us assume these readings mean the air is “okay.” Here’s the reality check: even at these lower levels, the air can be harmful. Why? Because AQI doesn’t tell us the whole story. PM2.5 does, and it’s the real silent killer that we should be watching.
Dr. Poornima Prabhakaran, Director of the Centre for Health Analytics and Trends (CHART) at Ashoka University emphasises that the true danger isn’t just in the alarming spikes we see every year, but in the everyday pollution levels. These are levels that almost drop to what the World Health Organization (WHO) considers safe. Dr Prabhakaran, is also a senior research scientist at the Center for Chronic Disease Control (CCDC) where she works closely with the Ministry of Health and Family Welfare (MoHFW) in the government of India.
Speaking to journalist Chetan Bhattacharji on Earth Chakra, Dr Prabhakaran highlights that a key cause for confusion is the difference between PM2.5 and AQI.
PM2.5 refers to pollutant particles smaller than 2.5 micrometres. “These are tiny enough to enter the lungs, cross into the bloodstream, and affect every organ system,” she explains, PM2.5 is directly linked to asthma, chronic lung disease, heart attacks, and stroke.
AQI, in contrast, is a composite score – a communication tool that converts multiple pollutants into a single number ranging from 0 to 500 in India’s National AQI; other countries and organisations can have AQIs with different limits, for example, 100 or 1,000. “AQI was designed as a messaging indicator,” Dr. Prabhakaran clarifies. “But PM2.5 is the real danger we should be tracking.”
What makes the problem worse, she points out, is public complacency. Pollution levels that people casually dismiss as ‘chaltahai’ are far from safe. “Exposure to even low levels of PM2.5 carries serious risks,” she warns. Meaningful change in public behaviour and policy requires India to adopt a scientific, evidence-driven approach to air governance.
According to Dr. Prabhakaran, progress will demand long-term commitment. “What we need is sustained political and public will,” she stresses. India is currently not meeting the World Health Organization’s (WHO) air quality recommendations. The WHO’s safe guideline for PM2.5 is an average of 15 micrograms per cubic metre over 24 hours; however the Central Pollution Control Board (CPCB) chart’s safe limit is 30 micrograms. But recognising PM2.5 as the core threat is a crucial step.
If clean air is a fundamental right, then securing it will demand steady, science-backed action from policymakers and citizens alike. Only by focusing on the pollutants that truly harm us, not just the numbers that simplify them, can India begin to reclaim the air it deserves to breathe.