How Much Air Pollution Could Be Fatal?

About 33,000 People Die in India’s 10 Cities Every Year Due to Pollution

Newsreel Asia Insight #272
July 5, 2024

A new study examining the effects of exposure to fine particulate matter (PM2.5) on daily death rates across 10 Indian cities has indicated that even modest increases in PM2.5 levels can elevate the daily death rate. The study also revealed that locally sourced pollution significantly intensifies the impact on mortality rates.

The study, published by The Lancet Planetary Health on July 4, analysed data spanning from 2008 to 2019, focusing on the cities of Ahmedabad, Bangalore, Chennai, Delhi, Hyderabad, Kolkata, Mumbai, Pune, Shimla and Varanasi.

According to the study, air pollution is attributable to 33,000 yearly deaths in these 10 cities.

The study revealed that just 48 hours of exposure to high levels of these particles could reduce the overall life expectancy, attributing 7.2% of all deaths to PM2.5 levels exceeding the World Health Organization’s guideline of 15 micrograms per cubic metre.

PM2.5 refers to tiny particles in the air that are less than 2.5 micrometres in diameter, which is about 30 times smaller than a human hair. These particles are so small that they can be inhaled deep into the lungs, potentially causing health problems.

While exposure to high levels of the particles are enough to adversely affect the life expectancy, the study showed that in these 10 cities, PM2.5 levels surpassed the WHO’s safe limit on 99.8% of the days.

The researchers found that a small increase in PM2.5 levels (by just 10 micrograms per cubic metre) could raise the daily death rate by 1.4%. This indicates that even slight rises in air pollution can result in more people dying each day.

The findings indicate that cities like Bengaluru and Shimla, which typically experience lower levels of air pollution, demonstrated stronger adverse effects. This is probably because health risks increase quickly at lower pollution levels, but this increase slows down at higher levels, which these cities rarely experience, explained Dr. Siddharth Mandal, from the Centre for Chronic Disease Control, who co-authored the study.

Further, when focusing on pollution that’s produced locally rather than coming from far away, the impact on death rates was even more significant. They found a 3.6% increase in daily deaths, which suggests local sources of pollution might be particularly harmful.

The study also showed that air pollution levels well below what is currently considered safe in India (60 micrograms per cubic metre, compared to WHO’s 15 micrograms per cubic metre) still pose a high risk. The risk of death doubles when air quality worsens even slightly below this standard.

According to their calculations, about 7.2% of all daily deaths in the 10 cities could be linked to days when PM2.5 levels exceeded the much stricter WHO’s guideline (15 micrograms per cubic metre).

The data revealed extremely high pollution levels across the cities, with daily averages far exceeding WHO’s recommended limits nearly every day over 11 years. For example, Delhi’s pollution levels were sometimes as high as 617 micrograms per cubic metre—far above any safety guidelines.

Vehicle emissions and industrial activities are the top two factors contributing to high levels of air pollution in India, according to numerous studies and reports by environmental agencies and research institutions.

One of the primary responsibilities of the government is the enforcement of environmental regulations. Often, lax enforcement and insufficient penalties for non-compliance allow industries and vehicles to pollute beyond legal limits. Both state and central governments can be held accountable for not adequately enforcing existing air quality standards and for slow progress in updating these standards to meet international norms.