Air pollution remains one of the most widespread environmental health risks in the world. It affects densely populated cities, industrial areas, agricultural regions and even places located far from major emission sources.

The latest global results show that poor air quality is not limited to one continent. Countries in South Asia, Central Asia, Africa and the Middle East all appear among those recording the highest annual concentrations of fine particulate matter.

According to the 2025 World Air Quality Report, Pakistan recorded an annual average PM2.5 concentration of 67.3 micrograms per cubic metre. This was more than 13 times the World Health Organization’s annual air-quality guideline of 5 micrograms per cubic metre.

Quick answer: Pakistan was the most air-polluted country in 2025, with an annual average PM2.5 concentration of 67.3 µg/m³. Bangladesh ranked second at 66.1 µg/m³, while Tajikistan ranked third at 57.3 µg/m³.

Key Findings

• Pakistan recorded the world’s highest national annual average PM2.5 concentration in 2025.
• Bangladesh ranked second, followed by Tajikistan, Chad and the Democratic Republic of the Congo.
• India ranked sixth, with an annual average PM2.5 concentration of 48.9 µg/m³.
• Eight of the ten most air-polluted countries exceeded the WHO guideline by more than seven times.
• Only 14% of the cities included in the report met the WHO annual PM2.5 guideline.
• Monitoring gaps mean that country rankings should be interpreted cautiously.

The 10 Most Air-Polluted Countries in 2025

The following ranking is based on annual average PM2.5 concentrations published in IQAir’s 2025 World Air Quality Report. PM2.5 concentrations are expressed in micrograms per cubic metre of air, written as µg/m³.

Which Was the Most Air-Polluted Country in 2025?

Pakistan ranked as the most air-polluted country in the world in 2025, with an annual mean PM2.5 concentration of 67.3 µg/m³.

Although this represented a decline from 73.7 µg/m³ in 2024, the concentration remained approximately 13.5 times higher than the WHO annual guideline.

Pakistan’s air pollution is influenced by a combination of urban traffic, industrial emissions, fossil-fuel combustion, brick production, waste burning, agricultural residue burning and windblown dust. Winter weather can make the problem worse by trapping pollutants close to the ground.

Large cities and industrial regions can experience prolonged smog episodes, particularly during the cooler months. However, a country-level average should not be interpreted as meaning that every place within Pakistan experienced the same concentration.

Why Bangladesh Ranked Second

Bangladesh recorded an annual average PM2.5 concentration of 66.1 µg/m³ in 2025. This was lower than the 78.0 µg/m³ recorded in 2024, but still more than 13 times the WHO guideline.

Air pollution in Bangladesh is associated with rapid urbanisation, dense traffic, construction dust, brick kilns, industrial activity, household fuel use and open burning.

Dhaka and its surrounding industrial areas frequently experience high particulate concentrations. Population density also increases the number of people exposed to polluted air.

Tajikistan Recorded a Sharp Increase

Tajikistan ranked third, with an annual average PM2.5 concentration of 57.3 µg/m³. This was substantially higher than its 2024 average of 46.3 µg/m³.

Air quality in Central Asia can be affected by household heating, transport emissions, industrial sources, power generation and regional dust. Dry landscapes and windblown mineral particles may contribute to particulate pollution, although PM2.5 can also include combustion-generated particles.

Changes between years may reflect actual pollution conditions, differences in weather and changes in the number or location of monitoring stations.

Chad Fell From First to Fourth

Chad recorded an annual average PM2.5 concentration of 53.6 µg/m³ in 2025. This was much lower than the 91.8 µg/m³ reported for 2024, when Chad ranked first.

The large year-to-year difference should be interpreted cautiously. Chad has limited monitoring coverage, and measurements may be strongly influenced by the number, location and completeness of available stations.

Windblown mineral dust from the Sahara and Sahel can contribute substantially to particulate concentrations. Household fuel combustion, waste burning and local transport emissions may add further pollution in populated areas.

Democratic Republic of the Congo Ranked Fifth

The Democratic Republic of the Congo recorded an annual average PM2.5 concentration of 50.2 µg/m³ in 2025, placing it fifth.

Potential contributors include biomass burning, household solid-fuel use, road dust, transport emissions, waste burning, mining and industrial activities. Forest and vegetation fires can also affect regional air quality.

Monitoring remains limited across much of Central Africa. The national figure should therefore be treated as an estimate based on the available reporting network rather than a complete measurement of every part of the country.

India Ranked Sixth

India recorded an annual average PM2.5 concentration of 48.9 µg/m³ in 2025, compared with 50.6 µg/m³ in 2024. This placed India sixth among the countries and territories included in the IQAir ranking.

India’s air pollution has multiple sources, including vehicles, coal-based power generation, industrial emissions, household fuels, construction, road dust, waste burning and seasonal agricultural fires.

Weather and geography can intensify pollution in northern India during winter. Low wind speeds and temperature inversions restrict vertical mixing, allowing pollutants to accumulate near the surface.

India also contained three of the world’s four most polluted cities in the 2025 report. Loni recorded an annual average PM2.5 concentration of 112.5 µg/m³ and was identified as the most polluted city in the dataset.

Kuwait Recorded One of the Largest Increases

Kuwait’s annual average PM2.5 concentration increased from 30.2 µg/m³ in 2024 to 45.7 µg/m³ in 2025, placing it seventh.

Air pollution in Kuwait can arise from petroleum-related industries, power generation, traffic, construction and natural dust. Desert dust events can produce substantial particulate concentrations across the Arabian Peninsula.

PM2.5 rankings do not distinguish automatically between natural and human-generated particles. Source-specific studies are needed to determine how much pollution comes from dust, fuel combustion, industry and other activities.

Uganda Ranked Eighth

Uganda recorded an annual average PM2.5 concentration of 43.0 µg/m³ in 2025, slightly higher than the 41.0 µg/m³ reported in 2024.

Pollution sources may include road traffic, unpaved roads, waste burning, household biomass fuels, diesel generators, industry and construction.

Rapid urban growth can increase exposure when transport systems, waste management and emission controls do not expand at the same pace as the population.

Egypt Ranked Ninth

Egypt’s annual average PM2.5 concentration was 40.6 µg/m³ in 2025. This was slightly higher than the 39.8 µg/m³ recorded in 2024.

Emissions from traffic, industry, power generation, waste burning and agricultural burning can combine with windblown desert dust. The Cairo metropolitan region is particularly vulnerable because of its population, traffic density and industrial activity.

Uzbekistan Ranked Tenth

Uzbekistan and Iraq both recorded annual average PM2.5 concentrations of 38.1 µg/m³. IQAir placed Uzbekistan tenth and Iraq eleventh in its published ranking.

Uzbekistan’s air quality can be affected by fossil-fuel combustion, transport, industrial activity, household heating, construction and dust from arid landscapes.

The Aral Sea region is also associated with salt and dust emissions from exposed lakebed sediments. However, pollution conditions vary considerably between regions and cities.

What Is PM2.5?

PM2.5 refers to airborne particles with an aerodynamic diameter of 2.5 micrometres or less. These particles are approximately 30 times smaller than the width of an average human hair.

PM2.5 may include soot, smoke, sulphates, nitrates, organic compounds, metals, mineral dust and other materials. Some particles are emitted directly, while others form in the atmosphere through chemical reactions involving gases such as sulphur dioxide, nitrogen oxides and ammonia.

Their small size allows them to penetrate deeply into the respiratory system. Some components can enter the bloodstream, contributing to effects beyond the lungs.

PM2.5 Is Not the Same as AQI

PM2.5 concentration and the Air Quality Index are related but are not identical.

A country’s annual PM2.5 value describes long-term particulate pollution. It should not be confused with its live AQI on a particular day.

What Is the WHO PM2.5 Guideline?

The World Health Organization recommends an annual average PM2.5 concentration of no more than 5 µg/m³. It also recommends a 24-hour guideline of 15 µg/m³.

These are health-based guideline values rather than legally enforceable global limits. Individual countries may adopt different national air-quality standards.

The WHO guideline does not represent a sharp boundary between harmless and harmful air. Health risks can occur below national legal limits, and the risk generally increases as long-term exposure rises.

How Serious Was Global Air Pollution in 2025?

IQAir analysed monitoring data from 9,446 cities in 143 countries, regions and territories for its 2025 report.

Only 14% of the cities included in the report met the WHO annual PM2.5 guideline. Of the 143 countries and territories assessed, 130 exceeded the guideline.

Only 13 countries and territories recorded national annual averages at or below the WHO guideline:

• French Polynesia
• Puerto Rico
• United States Virgin Islands
• Barbados
• New Caledonia
• Iceland
• Bermuda
• Réunion
• Andorra
• Australia
• Grenada
• Panama
• Estonia

Why Are South Asian Countries Highly Ranked?

South Asia continues to experience some of the world’s highest measured PM2.5 concentrations. Pakistan, Bangladesh and India all appeared among the six most polluted countries in 2025.

No single source explains the region’s pollution. Important contributors include:

• Coal and other fossil-fuel combustion
• Industrial emissions
• Road transport
• Brick kilns
• Construction and road dust
• Open waste burning
• Crop-residue burning
• Household solid-fuel use
• Diesel generators
• Seasonal weather conditions

Pollution also crosses administrative and national boundaries. Smoke, dust and secondary particulate matter can travel hundreds or thousands of kilometres, making air-quality management a regional issue.

How Does PM2.5 Affect Human Health?

Long-term and repeated exposure to PM2.5 is associated with cardiovascular and respiratory disease. The World Health Organization identifies air pollution as a risk factor for conditions including ischaemic heart disease, stroke, chronic obstructive pulmonary disease, asthma and lung cancer.

Children, older adults, pregnant women and people with existing heart or lung disease may be particularly vulnerable. People working outdoors or living near major emission sources may also experience greater exposure.

Health effects are influenced not only by the concentration of particles but also by their chemical composition, duration of exposure and individual susceptibility.

What Causes High PM2.5 Concentrations?

Fossil-fuel combustion

Coal-fired power plants, factories, diesel engines, petrol vehicles and generators release particles and gases that can form secondary PM2.5.

Household fuel use

Burning wood, charcoal, crop residues, coal or dung for cooking and heating can create both indoor and outdoor air pollution.

Agricultural burning

Open burning of crop residues releases smoke containing fine particles and gaseous pollutants. Regional winds can transport the pollution far from the fields where burning occurs.

Waste burning

Burning mixed municipal waste releases particulate matter and potentially hazardous substances. The composition of emissions depends on the materials being burned.

Industry and construction

Industrial operations, brick production, cement manufacturing, mining and construction can generate both direct particulate emissions and precursor gases.

Natural dust and wildfires

Dust storms, wildfires and other natural events can substantially increase particulate pollution. Natural sources do not remove the health risk, but they may require different management approaches from industrial emissions.

Did Global Air Quality Improve in 2025?

The global picture was mixed. Among the countries included in IQAir’s comparison, 75 recorded lower annual PM2.5 concentrations than in the previous year, while 54 recorded increases. Two remained unchanged, and 12 were newly represented.

Pakistan, Bangladesh, Chad, the Democratic Republic of the Congo and India recorded lower national averages than in 2024. Tajikistan, Kuwait, Uganda, Egypt and Uzbekistan recorded increases.

A one-year improvement does not necessarily establish a long-term trend. Weather, wildfire activity, dust events, economic activity, policies and monitoring coverage can all change annual averages.

Limitations of Country Air-Pollution Rankings

Global rankings are useful for communicating the scale of air pollution, but they should not be treated as perfect or complete measurements.

1. Monitoring coverage is unequal

Some countries operate large networks of regulatory monitoring stations. Others may have only a small number of government, research or community sensors.

A country with limited coverage may have an annual average based on only a few locations. Those locations may not represent rural areas, smaller towns or regions far from the monitors.

2. Monitoring networks change

New stations may be added, older stations may stop reporting and the geographical distribution of monitors may change. These changes can affect country averages and year-to-year comparisons.

3. Weather influences annual concentrations

Wind, rainfall, temperature, atmospheric mixing, dust storms and wildfires can increase or decrease measured PM2.5 independently of long-term emission policies.

4. Country averages hide local differences

Pollution may be severe in one industrial or urban region but much lower in another. A single national average cannot describe the exposure of every resident.

5. The ranking covers PM2.5, not every form of pollution

A country may have serious nitrogen dioxide, ozone, sulphur dioxide, water pollution, soil contamination or waste-management problems without appearing near the top of a PM2.5 ranking.

Important: This article ranks countries by reported annual average PM2.5 concentrations. It does not rank overall cleanliness, waste management, water quality or total environmental performance.

Are These the World’s “Dirtiest” Countries?

No. Air pollution and general environmental cleanliness are different concepts.

The word “dirty” may refer to waste accumulation, sanitation, contaminated water, poor environmental governance or visible litter. Annual PM2.5 rankings measure only one specific form of air pollution.

A country can have poor air quality but comparatively effective waste collection. Another country may have lower PM2.5 levels but serious problems involving plastic waste, wastewater or contaminated soil.

For a broader discussion, read:

Which Is the Dirtiest Country in the World?

How Can Countries Reduce PM2.5 Pollution?

Effective air-quality management requires action across several sectors rather than relying on a single intervention.

• Expand reliable air-quality monitoring networks.
• Enforce emission standards for power plants and industries.
• Reduce dependence on high-emission fuels.
• Improve public transport and vehicle-emission controls.
• Control dust from roads, construction and mining.
• Provide cleaner household cooking and heating options.
• Prevent open burning of waste.
• Support alternatives to agricultural residue burning.
• Improve waste collection and disposal systems.
• Coordinate policies across cities, states and national borders.
• Publish transparent and accessible air-quality data.

Since PM2.5 can travel across regions, local action remains necessary but may not be sufficient. Regional cooperation is essential where pollution crosses administrative boundaries.

What Can Individuals Do During Severe Air Pollution?

Individual action cannot replace emission control, but people can reduce personal exposure during severe pollution episodes.

• Check official local air-quality information before outdoor exercise.
• Reduce strenuous outdoor activity when particulate concentrations are high.
• Keep windows closed during severe outdoor smoke or dust events when indoor conditions are cleaner.
• Use a well-fitted particulate respirator when exposure cannot be avoided.
• Avoid smoking and indoor burning.
• Use effective filtration where practical.
• Follow medical advice if you have asthma, heart disease or another vulnerable condition.

These measures reduce exposure but do not solve the underlying pollution problem. The greatest health benefits come from sustained reductions in emissions across the population.

Frequently Asked Questions

Which was the most air-polluted country in the world in 2025?

Pakistan ranked first in IQAir’s 2025 country ranking, with an annual average PM2.5 concentration of 67.3 µg/m³.

Which countries had the worst air quality in 2025?

The five highest-ranked countries were Pakistan, Bangladesh, Tajikistan, Chad and the Democratic Republic of the Congo.

What was India’s air-pollution rank in 2025?

India ranked sixth, with an annual average PM2.5 concentration of 48.9 µg/m³.

What is a safe annual PM2.5 concentration?

The World Health Organization recommends an annual average PM2.5 concentration of no more than 5 µg/m³. This is a health-based guideline rather than a universally enforceable legal standard.

Why do pollution rankings change every year?

Rankings can change because of emissions, weather, dust storms, wildfires, government policies, economic activity and changes in monitoring coverage.

Is AQI the same as PM2.5?

No. PM2.5 is a measured pollutant concentration, while AQI converts pollutant levels into an index designed to communicate health risk.

Does a lower annual concentration mean that the air is safe?

Not necessarily. A country may improve compared with the previous year while still remaining far above the WHO guideline. National averages may also hide severe pollution in particular cities or seasons.

Can natural dust cause a country to rank highly?

Yes. Desert dust and other natural particles can raise PM2.5 concentrations. However, many highly polluted countries also experience substantial emissions from transport, industry, fuel combustion and waste burning.

Conclusion

Pakistan was the most air-polluted country in the world in 2025 according to IQAir’s annual PM2.5 ranking. Bangladesh, Tajikistan, Chad and the Democratic Republic of the Congo completed the top five, while India ranked sixth.

The results show that dangerous particulate pollution remains widespread across South Asia, Central Asia, Africa and the Middle East. Most of the countries at the top of the ranking recorded concentrations many times higher than the WHO annual guideline.

These rankings should nevertheless be interpreted carefully. Monitoring networks differ substantially among countries, annual averages hide local variation and PM2.5 represents only one dimension of environmental pollution.

The most important conclusion is not simply which country ranked first. It is that most of the world’s monitored population continues to breathe air containing particulate concentrations above health-based recommendations.

Related Reading

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  Which Is the Dirtiest Country in the World?
  
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  Climate Change and Its Environmental Impacts
  
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  Impact of Climate Change on Biodiversity
  
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  Ecosystem Services: Definition and Types
  

Sources and Further Reading

1. IQAir. 2026
   
   2025 World Air Quality Report: Key Findings
   
2. IQAir. 2026
   
   Most Polluted Countries and Regions: 2025 PM2.5 Ranking
   
3. World Health Organization. 2021
   
   WHO Global Air Quality Guidelines
   
4. World Health Organization. 2026
   
   WHO Ambient Air Quality Database, Version 8.0
   
5. World Health Organization
   
   Ambient Outdoor Air Pollution and Health