World Air Quality Report 2024

PM2.5, expressed in micrograms per cubic meter (μg/m3), has severe impacts on health, leading to its global recognition and monitoring as a key air pollutant. It can be generated by natural sources like wildfires or dust and sand storms, but the bulk is generated by human activity such as industrial activities, combustion engines, power generation, crop burning and so on.

The report stresses the greater impact of PM2.5 pollution on children, and the way it can lead to developmental issues and reduced lung function increasing risk of bronchitis and asthma.

The 2023 report listed Bangladesh as the country with the highest concentration of PM2.5 levels at 79.9 μg/m3. In the 2024 report, Chad surpasses Bangladesh with PM2.5 levels equalling 91.8 μg/m3. It is followed by Bangladesh (78.0 μg/m3), Pakistan (73.7 μg/m3), the Democratic Republic of Congo (58.2 μg/m3) and India, which has gone down from third place in 2023 (54.4 μg/m3) to fifth place in 2024 (50.6 μg/m3).

The Bahamas recorded the lowest PM2.5 concentrations at 2.3 μg/m3. Bermuda and French Polynesia both followed closely with 2.5 μg/m3, with U.S. Virgin Islands (2.6 μg/m3) and Puerto Rico (2.7 μg/m3) trailing with the next lowest levels.

The report also ranks the capital cities of each country along the same parameters. In 2024, New Delhi retained its spot as the capital city with the highest PM2.5 concentration - 91.8 μg/m3. However, these levels were lower than those recorded the previous year. It was followed by N’Djamena, Chad (91.6 μg/m3), Dhaka, Bangladesh (78 μg/m3), Kinshasa, Democratic Republic of Congo (58.2 μg/m3) and Islamabad, Pakistan (52.4 μg/m3).

Among cities, the lowest average concentrations were recorded in Nassau, Bahamas (2.3 μg/m3). Nassau was tailed by San Juan, Puerto Rico (2.6 μg/m3), Papeete, French Polynesia (2.8 μg/m3), Bridgetown, Barbados (3.1 μg/m3) and Reykjavik, Iceland (3.8 μg/m3).

The report notes a decline in India’s PM2.5 levels by seven per cent in 2024 as compared to 2023 – from 54.4 μg/m3 to 50.6 μg/m3. New Delhi’s PM2.5 concentration also declined in the same period from 102.1 μg/m3 in 2023 to 91.6 μg/m3 in 2024. In Delhi, as in other urban centres, vehicular emissions and industrial activity contributed significantly to PM2.5 concentrations.

As per the data, six out of the ten most polluted cities globally are Indian cities. The WHO guideline for PM2.5 concentrations is 5 μg/m3, but over 35 per cent of Indian cities have averages exceeding 10 times this value.

The report outlines steps to decrease air pollution emissions and expand the framework for monitoring air quality. It advocates for access to hyperlocal air quality data, especially linked with student health. It also calls for governments to expand funding to renewable energy projects and increase use of clean energy in public transport systems.

Focus and Factoids by Achinthya Sriman.

PARI Library's health archive project is part of an initiative supported by the Azim Premji University to develop a free-access repository of health-related reports relevant to rural India.