Dirtiest Countries in the World 2025

Pollution is the introduction or presence of contaminants that can have a damaging effect on the natural environment. The two most prominent forms of pollution are air and water pollution, though many other forms exist. For example: sound, light, and soil pollution.

Many forms of pollution can have a broad and long-lasting negative impact upon the health of humans, plants and animals, or entire ecosystems.

Air Pollution and its Impact

Air pollution is primarily introduced through the burning of fossil fuels. The largest contributors are fossil-fuel-powered vehicles (cars, trucks, aircraft, ships, etc.) and coal- or oil-burning power plants and factories. However, any activity that involves the burning of wood or fossil fuels can release particulate matter. This includes household-level sources such as tobacco products, stoves and ovens, candles, and fireplaces. Volcanos and wildfires can also be notable sources of air pollution.

Air pollution has been proven to contribute to health problems including breathing issues, worsening of asthma, and even congenital disabilities. According to Pure Earth, toxic pollution is among the leading risk factors for non-communicable diseases globally. Non-communicable diseases account for 72% of all deaths, 16% of which are caused by toxic pollution. Toxic pollution is responsible for 22% of all cardiovascular disease, 25% of stroke deaths, 40% of lung cancer deaths, and 53% of deaths from chronic obstructive pulmonary disease.

This aligns with data from the World Health Organization (WHO), which indicates that air pollution causes 7 million premature deaths every year. 91-99% of the world’s population lives in places where air quality exceeds WHO recommended guidelines.

Particle Pollution

The United States Environmental Protection Agency measures five major pollutants, all of which are regulated via the Clean Air Act:

• ground-level ozone
• particle pollution (also known as particulate matter, including PM_2.5 and PM₁₀)
• carbon monoxide
• sulfur dioxide
• nitrogen dioxide

Of these, particle pollution is the most commonly monitored. The World Health Organization evaluated the concentration of PM_2.5 particles to determine the most polluted place on Earth. PM_2.5 (fine particulate matter 2.5) refers to tiny particles or droplets in the air that are 2.5 microns (µg) or less in diameter.

PM_2.5 is an air pollutant and can be a health concern when present in high concentrations. Cities such as New York, issue a PM_2.5 Health Advisory when conditions are considered to be unhealthy for sensitive groups. In recent years, wildfires have triggered an increasing number of PM_2.5 warnings in many other regions as well, including portions of Europe, Australia, Africa, and the western United States.

The World Health Organization (WHO) target for air pollution is 0-10 µg/m³. IQ Air, which measures pollution in 109 countries around the globe, considers measurements above 35.5 to be unhealthy for sensitive groups, levels between 55.5 and 150.4 to be unhealthy for all, and anything higher is either very unhealthy (150.5-250.4) or hazardous (250.5 or higher).

Top 10 Countries with the Worst Air Pollution - PM_2.5 exposure (µg/m³) - 2024

While the IQ Air list is respectable, it is not the only available source of air pollution data. Using data from Seattle, Washington’s Institute for Health Metrics and Evaluation, the Health Effects Institute has released its own list ranking the levels of air pollution of 196 nations via the State of Global Air report.

The Air Quality Index (AQI) used by the United States Environmental Protection Agency is slightly more lenient than the IQ Air scale (by about 50 µg/m³). Values of 0-100 are generally thought of as satisfactory. However, values from 101-200 are considered unhealthy for certain at-risk groups, values 201-300 are viewed as unhealthy for everyone, and levels above 300 are deemed hazardous for all.

The cleanest countries in the world, as determined by the Environmental Performance Index (EPI), have high air quality, clean water, and strong environmentally-friendly policies and initiatives. These countries include Switzerland, France, and Denmark.

As the damage from pollution has become more apparent, more countries are looking to green alternatives to prevent further damage to the Earth. Solar and wind energy, eco-friendly building materials, and non-toxic products are increasingly being used to preserve the planet. While these green initiatives are taking place around the world, some countries have a long way to go.

Country-by-country Profiles of the Nations with the Worst Air Pollution in the World (per IQ Air 2022)

1. Chad

In a concerning trend, Chad has ascended to the top of the list as the world’s most polluted country in 2022, with a PM2.5 concentration of 89.7, quite a jump from 75.9 in 2021. The air quality crisis thus continues to worsen, driven by such factors as desert dust, vehicle emissions, and biomass burning. Chad’s capital, N’Djamena, frequently grapples with dust storms that blanket the city. The country’s increasing reliance on biomass as a primary energy source for cooking and heating continues to raise indoor pollution, with dire health implications for its population, particularly affecting vulnerable groups like children and women.

2. Iraq

Iraq’s pollution has taken a sharp upward trajectory, moving from a PM2.5 concentration of 39.6 in 2019 to a startling 80.1 in 2022. This alarming rise points to escalating environmental challenges stemming from industrial growth, traffic congestion, and recurrent dust storms. The ongoing conflict makes the situation worse, damaging infrastructure and raising dust levels. Such urban centers as Baghdad are particularly affected, with residents facing the brunt of pollution from traffic and industrial activities, including significant contributions from the oil sector’s gas flaring practices.

3. Pakistan

Pakistan’s air quality saga is marked by fluctuations, with the PM2.5 concentration peaking at 74.3 in 2018, dipping to 59 in 2020, and climbing back to 70.9 in 2022. This seesaw pattern reflects the ongoing struggle against such air pollution sources as vehicle emissions, industrial discharges, and agricultural burning. Urban areas, notably Lahore and Karachi, are hotspots for hazardous air, impacting millions. The government’s efforts to curb pollution face the uphill task of balancing economic growth with environmental sustainability. The Pakistan minister for climate change blamed India for Pakistan’s smog; however, Pakistani citizens blame their government for simply not doing enough to monitor or combat the crisis.

4. Bahrain

Bahrain’s journey through the pollution scale reveals a complex pattern, with a PM2.5 concentration that fluctuated from 59.8 in 2018, reduced to 39.7 in 2020, and then spiked to 66.6 in 2022. These fluctuations reflect the challenges posed by industrial emissions, heavy traffic, and regional dust storms. The petroleum industry, central to Bahrain’s economy, is a significant pollution contributor. The capital, Manama, often enveloped in smog, epitomizes the country’s struggle with air quality.

5. Bangladesh

Once the most polluted country in the world, Bangladesh’s saw slight air quality improvement amidst ongoing challenges. From the world’s highest PM2.5 concentration of 97.1 in 2018, it has gradually decreased to 65.8 in 2022, albeit still ranking among the worst globally. The drop from 76.9 in 2021 indicates some progress, yet the air quality in Dhaka and other urban areas remains perilously poor. In terms of air pollution, Bangladesh’s largest source is its brickmaking industry, which employs one million people and creates 23 billion bricks every year. Vehicle and industrial emissions add to clouding the air, necessitating urgent and effective pollution control measures to protect public health.