N’Djamena was the most polluted capital city in the world in 2024, with an average annual PM2.5 concentration of nearly 92 micrograms per cubic meter of air (μg/m³). PM2.5 particulate matter concentrations in the Chad capital were over 18 times higher than the World Health Organizations PM2.5 guideline of five μg/m³. New Delhi followed closely in second place, with PM2.5 levels of 91.6 μg/m³. Sources of PM2.5 PM2. 5 refers to atmospheric particulate matter that have a diameter of less than 2.5 micrometers. There are many sources of PM2.5 emissions, including road transport, industrial activities, crop burning, and energy industries. Domestic combustion, such as burning wood for fuel, is also a major source of PM2.5 emissions. As a result, PM2.5 concentrations are typically higher in developing countries. Health impacts of air pollution Exposure to high levels of PM2.5 increases the likelihood of heart and lung problems, and can lead to premature death. Air pollution is one of the leading causes of premature deaths worldwide, cutting millions of lives short every year. Although the highest number of annual air pollution-related deaths are observed in East Asia and Pacific, the health and lives of people in all regions of the world are at risk from harmful pollutants like PM2.5.

The city of Byrnihat in Meghalaya, India was the most polluted city in the world in 2024, with average annual PM2.5 concentration of nearly *** micrograms per cubic meter of air (μg/m³). This was roughly ** times above the WHO PM2.5 recommended guideline. More than half of the ** most polluted cities in the world in 2024 were located in India, including New Delhi, which was the most polluted capital city in the world that year.

Sarajevo was the most polluted capital city in Europe in 2024, with an average PM2.5 concentration of 30.8 micrograms per cubic meter of air (μg/m³). This level of air pollution was roughly six times higher than World Health Organization guidelines. The second most polluted capital city in Europe that year was Skopje, North Macedonia, with an average PM2.5 concentration of 21.6 μg/m³.
How bad is air pollution in Europe? Poor air quality is a major issue in Europe, particularly in cities. In fact, more than 90 percent of the EU urban population were exposed to PM2.5 concentrations above WHO guidelines in 2021. Average annual PM2.5 levels in populated European cities like Rome, Berlin, and Paris are often double recommended limits. Sources of particulate matter emissions There are several sources of PM2.5 emissions in the European Union, including transportation, energy supply, and agriculture, but the biggest contributor is the residential, commercial, and institutional sector. While PM2.5 emissions from other sectors have fallen notably since the turn of the century, residential, commercial, and institutional emissions have seen little change.

Chad was the most polluted country in the world in 2024, with an average annual PM2.5 concentration of ** micrograms per cubic meter of air (µg/m3). These levels were around ** times above the World Health Organization guideline. Major sources of PM2.5 include residential fuel burning, road vehicles, and power plants. What are PM2.5 pollutants PM2.5 refers to fine particles that have a diameter of 2.5 micrometers or less. These tiny, light, and inhalable pollutants can stay in the air for long periods of time and are a considerable risk to human health when concentrations are high. There were an estimated ***** million premature deaths linked to air pollution worldwide in 2021, of which ** percent were attributed to ambient PM2.5. Pollution in cities In 2024, N'Djamena, Chad and New Delhi, India were the most polluted capital cities in the world, with average annual PM2.5 concentrations of ** µg/m³. In 2024, ** of the ** most polluted cities worldwide were in India, the most polluted of which recorded PM2.5 levels ** times above WHO standards.

Abstract

Polluted air is a major health hazard in developing countries. Improvements in pollution monitoring and statistical techniques during the last several decades have steadily enhanced the ability to measure the health effects of air pollution. Current methods can detect significant increases in the incidence of cardiopulmonary and respiratory diseases, coughing, bronchitis, and lung cancer, as well as premature deaths from these diseases resulting from elevated concentrations of ambient Particulate Matter (Holgate 1999).

Scarce public resources have limited the monitoring of atmospheric particulate matter (PM) concentrations in developing countries, despite their large potential health effects. As a result, policymakers in many developing countries remain uncertain about the exposure of their residents to PM air pollution. The Global Model of Ambient Particulates (GMAPS) is an attempt to bridge this information gap through an econometrically estimated model for predicting PM levels in world cities (Pandey et al. forthcoming).

The estimation model is based on the latest available monitored PM pollution data from the World Health Organization, supplemented by data from other reliable sources. The current model can be used to estimate PM levels in urban residential areas and non-residential pollution hotspots. The results of the model are used to project annual average ambient PM concentrations for residential and non-residential areas in 3,226 world cities with populations larger than 100,000, as well as national capitals.

The study finds wide, systematic variations in ambient PM concentrations, both across world cities and over time. PM concentrations have risen at a slower rate than total emissions. Overall emission levels have been rising, especially for poorer countries, at nearly 6 percent per year. PM concentrations have not increased by as much, due to improvements in technology and structural shifts in the world economy. Additionally, within-country variations in PM levels can diverge greatly (by a factor of 5 in some cases), because of the direct and indirect effects of geo-climatic factors.

The primary determinants of PM concentrations are the scale and composition of economic activity, population, the energy mix, the strength of local pollution regulation, and geographic and atmospheric conditions that affect pollutant dispersion in the atmosphere.

Geographic coverage

The database covers the following countries: Afghanistan Albania Algeria Andorra Angola
Antigua and Barbuda Argentina
Armenia Australia
Austria Azerbaijan
Bahamas, The
Bahrain Bangladesh
Barbados
Belarus Belgium Belize
Benin
Bhutan
Bolivia Bosnia and Herzegovina
Brazil
Brunei
Bulgaria
Burkina Faso
Burundi Cambodia
Cameroon
Canada
Cayman Islands
Central African Republic
Chad
Chile
China
Colombia
Comoros Congo, Dem. Rep.
Congo, Rep. Costa Rica
Cote d'Ivoire
Croatia Cuba
Cyprus
Czech Republic
Denmark Dominica
Dominican Republic
Ecuador Egypt, Arab Rep.
El Salvador Eritrea Estonia Ethiopia
Faeroe Islands
Fiji
Finland France
Gabon
Gambia, The Georgia Germany Ghana
Greece
Grenada Guatemala
Guinea
Guinea-Bissau
Guyana
Haiti
Honduras
Hong Kong, China
Hungary Iceland India
Indonesia
Iran, Islamic Rep.
Iraq
Ireland Israel
Italy
Jamaica Japan
Jordan
Kazakhstan
Kenya
Korea, Dem. Rep.
Korea, Rep. Kuwait
Kyrgyz Republic Lao PDR Latvia
Lebanon Lesotho Liberia Liechtenstein
Lithuania
Luxembourg
Macao, China
Macedonia, FYR
Madagascar
Malawi
Malaysia
Maldives
Mali
Mauritania
Mexico
Moldova Mongolia
Morocco Mozambique
Myanmar Namibia Nepal
Netherlands Netherlands Antilles
New Caledonia
New Zealand Nicaragua
Niger
Nigeria Norway
Oman
Pakistan
Panama
Papua New Guinea
Paraguay
Peru
Philippines Poland
Portugal
Puerto Rico Qatar
Romania Russian Federation
Rwanda
Sao Tome and Principe
Saudi Arabia
Senegal Sierra Leone
Singapore
Slovak Republic Slovenia
Solomon Islands Somalia South Africa
Spain
Sri Lanka
St. Kitts and Nevis St. Lucia
St. Vincent and the Grenadines
Sudan
Suriname
Swaziland
Sweden
Switzerland Syrian Arab Republic
Tajikistan
Tanzania
Thailand
Togo
Trinidad and Tobago Tunisia Turkey
Turkmenistan
Uganda
Ukraine United Arab Emirates
United Kingdom
United States
Uruguay Uzbekistan
Vanuatu Venezuela, RB
Vietnam Virgin Islands (U.S.)
Yemen, Rep. Yugoslavia, FR (Serbia/Montenegro)
Zambia
Zimbabwe

Kind of data

Observation data/ratings [obs]

Mode of data collection

Other [oth]

Santa María – a Peruvian city located to the west of the Andes mountain range – was the most polluted city in Latin America in 2024, based on fine air particulate matter concentration (PM2.5). That year, the city reported an average PM2.5 concentration of 53.4 micrograms per cubic meter. This was followed by Coyhaique, located in Chile, with an estimated PM2.5 concentration of around 40.5 μg/m³. Pollution in Latin American capitals The Chilean capital, Santiago, registered an average PM2.5 concentration of 21.3 μg/m³ in 2023. Lima, the Peruvian capital, had an estimated PM2.5 concentration of around 19.7 μg/m³, while in the capital of Mexico (Mexico City), air pollution amounted to 22.3 μg/m³. The World Health Organization's air quality standards recommend a maximum annual average concentration of 10 μg/m³. The burden of pollution on health Air particulate pollution has been associated with an increase in mortality from cardiovascular and respiratory diseases, as well as development of lung cancer. This is specially concerning considering that nearly 2.8 billion people worldwide are exposed to hazardous levels of air pollution. In particular, South Asia was home to the countries with the highest exposure to hazardous concentrations of air pollution in 2022.

Ajaplan was the most polluted city in Mexico in 2024, based on fine air particulate matter concentration (PM2.5). Throughout the year, the city had an average particulate matter concentration of 24.3 micrograms per cubic meter. The average particulate matter pollution in the national capital Mexico City stood at 19.5 micrograms per cubic meter that year. How bad is fine air pollution in Mexico? Fine air particulate pollution (PM2.5) refers to particles with a diameter smaller than 2.5 micrometers. Due to their small size, once inhaled they can penetrate body tissue, and trigger respiratory issues such as asthma and allergies, in addition to being associated with an increase in mortality from cardiovascular and respiratory diseases. The World Health Organization's air quality standards recommend a maximum annual average concentration of 10 µg/m³. Nevertheless, Mexico's PM2.5 levels in 2024 averaged over 17 µg/m³. This positioned Mexico in 55th place amongst the countries with the highest PM2.5 concentration that year, far below Chad, which ranked first in the list with pollution levels reaching over 90 µg/m³. Mexico also had some of the cities with the highest air pollution across Latin America, together with Chile and Peru. Where are the world’s most polluted cities? Despite pollution levels above those recommended by the World Health Organization, Mexico City didn’t even make it to the top 25 most polluted capital cities in 2024. That year, the ranking was topped by Indian capital New Delhi, with an average PM2.5 concentration of nearly 108.3 µg/m³. In fact, the majority of the most air polluted cities worldwide in 2024 were located in India, with the average PM2.5 concentration reaching as high as 128.2 µg/m³. Pakistan also had some of the world’s most polluted cities.

Novi Pasar in Serbia had the highest average ***** concentration recorded in Europe in 2024, at roughly ** µg/m³. According to the World Health Organization, annual average ***** concentrations should not exceed **** µg/m³. Several of the most polluted cities in Europe in 2024 were in Bosnia and Herzegovina. The Balkan country's capital, Sarajevo, was also the most polluted European capital city that year. Cities in Bosnia and Herzegovina are often affected by high levels of air pollution due to the country's reliance on coal for heating and electricity generation. Every year, there are thousands of premature deaths linked to air pollution exposure in Bosnia and Herzegovina.

This statistic displays the most polluted cities in the world based on PM2.5 concentrations in 2016. During this year, Patna, India had an average PM 2.5 concentration of *** micrograms per cubic meter. The World Health Organization recommends that PM2.5 levels should not exceed ** micrograms per cubic meter.

Byrnihat was the most polluted city in India in 2024, with an average PM2.5 concentration of nearly 130 micrograms per cubic meter of air (μg/m³). This high level of pollution made the small industrial town on the Assam Meghalaya border the most polluted cities worldwide in 2024. Poor air quality across India India was the fifth-most polluted country in the world in 2024, with an average PM2.5 concentration of 50.6 μg/m³. That same year, the country's capital New Delhi was also the most polluted capital city in the world. Vehicle exhaust and wood burning are some of the main sources of particulate air pollution in India, together with soil, road and construction dust . Impacts of air pollution in India The severe air pollution in India can have detrimental health impacts on the country's population. Fine particle pollutants penetrate deeply in the lungs, causing respiratory problems and can even result in premature death. More than two million deaths are attibuted to air pollution in India every year.

In 2024, Bangladesh's capital Dhaka had a pollution index score of ****, the highest among megacities in the Asia-Pacific region. In contrast, Japan's capital Tokyo had a pollution index score of **** that year. Megacities on course for growth The United Nations defines megacities as cities with over ten million inhabitants. The population living in megacities has doubled in size in the last twenty years and is expected to rise even more until 2035. Today, the Asia-Pacific region is home to the highest number of megacities, with China and India alone accounting for around half of all megacities worldwide. At the same time, only half of the population in Asia is living in cities. This figure is also expected to rise exponentially over the next years, especially with much of the younger population migrating to larger cities. The growth of megacities and their higher population densities bring along several environmental problems. Exposure to pollution in India The most populated cities in APAC are located in Japan, China and India. As seen above, India's capital also falls among the top three most polluted megacities in the region and ranks second among the most polluted capital cities worldwide with an average PM2.5 concentration. As one of the fastest emerging economies in the world, India's rapid urbanization and industrialization have led to high pollution rates in different areas. The volume of emissions from coal-fired power plants has led to electricity and heat accounting for the largest share of greenhouse gas emissions in India. The country is also among the nations with the highest population share exposed to hazardous concentrations of air pollution worldwide.

Coyhaique, located to the east of the Andes mountain range, was the most polluted city in Chile in 2024, based on fine air particulate matter concentration (PM2.5). Throughout the year, the city had an average particulate matter concentration of 40.5 micrograms per cubic meter. Coyhaique also ranked as the second most polluted city in Latin America that year. The World Health Organization's air quality standards recommend a maximum annual average concentration of 10 μg/m³. Chile's capital Santiago reported an average PM2.5 concentration of 17.3 μg/m³ that year.

Acrelandia, located in the northern state of Acre, was the most polluted city in Brazil in 2022, based on fine air particulate matter concentration (PM2.5). Throughout the year, the city had an average particulate matter concentration of 23.3 micrograms per cubic meter. The World Health Organization's air quality standards recommend a maximum annual average concentration of 10 μg/m³. Four of the top five most polluted cities in Brazil that year were located in the state of Acre.

Sri Ganganagar in Jajasthan was India's most polluted city in 2024, based on average annual PM10 concentrations of 236 micrograms per cubic meter of air (µg/m³). This was roughly four times higher than India's National Ambient Air Quality Standards (NAAQS) for PM10, and more than 15 times above World Health Organization air quality guidelines.PM10 is suspended coarse particulate matter with a diameter of 10 micrometers or less. It can come from various sources, including dust from roads and agriculture, smoke from wildfires, and industrial sources. Long-term exposure to PM10 can result in serious health impacts, such as asthma, heart failure, and cancer, as well as premature death.

Saint-Denis was the most polluted city in France in 2024, with an average PM2.5 concentration of **** micrograms per cubic meter of air (μg/m³). This level exceeds World Health Organization guidelines by roughly three times. Meanwhile, Lyon had a PM2.5 concentration of *** μg/m³ that year.

Air pollution levels in cities vary greatly around the world, though they are typically higher in developing regions. In 2024, the cities of Jakarta and Cairo had an average PM2.5 concentrations of **** and **** micrograms per cubic meter (μg/m³) respectively. By comparison, PM2.5 levels in London and New York were less than ***** μg/m³. Nevertheless, pollution levels in these four major cities are all higher than the World Health Organization's healthy limit, which are set at an annual average of less than **** μg/m³. There are many sources of air pollution, such as energy production, transportation, and agricultural activities.

Muzza di Cornegliano Laudense was the most polluted city in Italy in 2024, with an average PM2.5 concentration of 28.2 micrograms per cubic meter of air (μg/m³). This level of air pollution exceeds World Health Organization PM2.5 guidelines by nearly six times. Cagliari had the second-highest PM2.5 concentration that year, at some 27.9 μg/m³.

In 2023, people in Nottingham were exposed to annual average particulate matter (PM2.5) concentrations of 9.1 micrograms per cubic meter of air (μg/m³). This was almost double the average PM2.5 concentration observed in Edinburgh, that year. The UK capital – London – had an average PM2.5 concentration of 8.4 μg/m³ in 2023. While this was considerably lower than PM2.5 concentrations in the most polluted capital cities in Europe, levels in London were still above World Health Organization guidelines of five μg/m³.

New Delhi was the most polluted city in India in 2024, based on an average air quality index (AQI) of ***. The seven most polluted cities in India in 2024 all had AQI levels above ***. An AQI between 151 and 200 is classified as unhealthy. Air pollution in India India was the third most polluted country in the world in 2023, behind only Bangladesh and Pakistan. The South Asian country recorded an average annual fine particulate matter (PM2.5) concentration of ** micrograms per cubic meter of air (µg/m3) that year, more than ** times above the World Health Organization’s recommended limit. Health effects of air pollution Exposure to air pollution can lead to a range of health issues, such as strokes, respiratory conditions, and cardiovascular disease. Air pollution is attributable to millions of premature deaths every year around the world, with India one of the most affected countries.

Milan had the highest average PM2.5 concentration among Europe's most populated cities in 2021 and 2022, with **** µg/m3. Milan sits in the Po Valley of Northern Italy, which is one of Europe's most polluted regions due to its geographical location and proximity to industrial activities. Poland's capital Warsaw ranked second, with average PM2.5 concentrations of **** µg/m3 based on levels measured in 2021 and 2022. Warsaw is prone to poor air quality due to factors such as burning solid fuels for household heating. Around ** percent of the European Union's urban population is exposed to PM2.5 concentrations above World Health Organization guidelines.