The first multi-city study to assess the relationship between short-term air pollution exposure and death in India

Assessed PM2.5 (ultrafine particulate matter with a diameter less than 2.5 micrometres) exposure in the ten cities and the daily mortality count between 2008 and 2019

Ten cities

Ahmedabad,
Bengaluru,
Chennai,
Delhi,
Hyderabad,
Kolkata,
Mumbai,
Pune,
Shimla and
Varanasi

The current Central Pollution Control Board (CPCB) standards set a daily limit of 25 micrograms per cubic metre for PM 2.5 and 50 micrograms per cubic metre for PM 10.

But the WHO limits are 15 micrograms per cubic metre of PM 2.5

About 33,000 deaths across 10 Indian cities each year between 2008 and 2019 can be attributed to air pollution levels exceeding the World Health Organization (WHO) guidelines

An increase of 10 microgram per cubic metre in short-term PM2.5 exposure was associated with a 1.42 percent increase in daily deaths. This estimate nearly doubled to 3.57 percent with specific local sources of pollution at play.

& India was declared the third most polluted country globally, after Bangladesh and Pakistan - World Air Quality Report 2023 by Swiss Air Quality Monitoring body
& Report’s list of the top 50 most polluted cities, 42 cities were from India.

The air pollution policy in India currently focuses on ‘non-attainment cities’, which fail to meet the current Indian standards

Researchers called for an increased focus on action year-round and not just on seasonal extremes

November 2025

Children are more vulnerable to PM 2.5

Children take in more air per kilogram of body weight than adults - European Environment Agency.

PM 2.5 more hazardous than PM 10

40% of the PM 2.5 children inhaled travelled to the deepest part of the lungs. The infants are also affected by this. This makes it hazardous pollutant for infants and children than PM 10. - Centre for Research on Energy and Clean Air (CREA)

Reason for vulnerability in children

Children are vulnerable because their lungs are still developing, their airways are narrower, and they breathe more rapidly than adults. Hence, they breathe in more unfiltered air through their mouths that bypasses the nasal filtration.

PM 10 gets trapped, while PM 2.5 escapes

Mostly the PM10 gets trapped in the head and throat area, which is around 55-95 per cent, and only 2-4 per cent manages to penetrate children’s deep lungs.

But on the other side, PM2.5 consistently fights these upper defences and enters in a heavy amount in the pulmonary region, which is the most vulnerable, and it takes time to clear.

It is difficult to get cleared as it is harder for the lower lobes to clear away those particles than the upper airways. That gives them more time to trigger inflammation, respiratory diseases and long-term damage.

PM 2.5 accounts for more pollution than PM 10

Current pollution control policies still prioritise PM10 despite PM2.5 making up nearly 70 per cent of Delhi’s particulate pollution load during winter.

2020 school based study

A 2020 school-based study from Bogotá also found that 93 per cent of the world’s children under 15 are exposed to PM2.5 levels above WHO guidelines, and young children inhale disproportionately higher doses during routine school activities.

According to this research, children aged three to five breathed the highest amount of PM2.5 and also reported more respiratory symptoms. Print