Toxicity: 15% of deaths in Delhi linked to air pollution, says study

NEW DELHI: One in seven deaths in Delhi in 2023 were due to polluted air, states the latest Global Burden of Disease (GBD) data released this month by the Institute for Health Metrics and Evaluation (IHME).An analysis of the data by the Centre for Research on Energy and Clean Air (CREA) shows that ambient particulate matter pollution remains the single largest risk factor for deaths in Delhi, accounting for nearly 15% of all fatalities in 2023,numbering around 17,200.“In 2023, 9.4% of Delhi’s total disability-adjusted life years (DALYs) were attributable to particulate pollution, the highest in the country. This equates to nearly 4.9 lakh years of healthy life lost by Delhi’s population due to polluted air,” said Manoj Kumar, an analyst at CREA.

‘Prolonged exposure to polluted air causes diseases to gradually worsen’

He pointed out that unless Delhi’s air quality improves substantially, the health burden from pollution-related diseases, especially respiratory illnesses, heart disease, stroke, and lung cancer, will continue to rise.Following air pollution, other major risk factors contributing to 2023 mortality in the city include high systolic blood pressure (14,874 deaths, 12.5%), high fasting plasma glucose (10,653 deaths, 9%), high cholesterol (7,267, 6%) and high body-mass index (6,698, 5.6%).

Doctors, while asserting that pollution kills, however, point out that it’s complex to quantify such deaths.Dr Harshal Ramesh Salve, additional professor at AIIMS, said the numbers can be debated. “No doubt excessive mortalities are happening due to pollution. However, the quantum is debatable. It is all about the estimates. These figures depend on mathematical modelling and none of the models are perfect. There is something called the exposure response function, which is used to make such estimates, and which we don’t have for the Indian population,” Dr Salve said, adding that the increasing trend in mortality attribution makes an urgent case for multi-sectorial action.According to Dr Nikhil Modi, senior consultant for Respiratory and Critical Care at Indraprastha Apollo Hospitals, the 15% figure is believable. “When we talk about deaths caused by air pollution, it essentially means that prolonged exposure to polluted air leads to diseases that can graduallyworsen and eventually result in death. Pollution-related mortality has certainly increased over the past few years.

While it is difficult to determine the exact figures without comprehensive studies, the estimate that around 15% of deaths are linked to pollution appears quite plausible. If the situation is not addressed soon, we are likely to see a further rise in pollutionrelated deaths,” Dr Modi said.Dr Neetu Jain, senior pulmonologist at PSRI Hospital, pointed out that while quantifying mortalities is complex, studies have linked very high mortality risks due to long-term PM2.5 exposure — especially from heart disease, stroke, lung cancer, chronic obstructive pulmonary disease (COPD), and lower respiratory infections.

“When we say 15% of all deaths are linked to air pollution, it doesn’t mean pollution directly kills in an acute sense every time.

Rather, it acts as a chronic, invisible stressor that accelerates or worsens underlying conditions. For example, prolonged inhalation of PM2.5 triggers systemic inflammation, oxidative stress and impaired lung and cardiac function. Over years, this increases the likelihood of premature death.”Dr Jain added: “While it’s true that quantifying exact numbers is complex — since deaths are not registered as ‘due to pollution’ on certificates — these estimates are derived from robust epidemiological models using population exposure data, disease burden and mortality trends. So, while 15% may sound staggering, it is scientifically plausible given Delhi’s consistently high pollution levels and population vulnerability.

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