The 5 World Capital Cities with the Absolute Worst Air Quality

Humans take about 22,000 breaths a day. Breathing powers the bodies of all animals on Earth except for one recently discovered creature. That leaves the millions of other species on the planet dependent on oxygen from air or water for life-sustaining fuel. Sometimes, however, air is crowded with pollutants that the body absorbs along with vital oxygen. In the five world capital cities with the worst air quality, the simple act of breathing can be dangerous.

Effects of Poor Air Quality

Health

Air pollution is the world’s largest environmental health threat, according to the 2022 World Air Quality Report. Poor air quality takes a huge toll on human populations. This is especially true for vulnerable groups like the elderly, children, pregnant women, and those with chronic illnesses.

Worldwide, polluted air kills six million people a year, 90 percent of whom live in low- and middle-income countries. It accounts for 93 billion days lived with illness. Air pollution is the major environmental driver associated with a variety of diseases. Such health problems include Alzheimer’s and Parkinson’s diseases, low birth rates, asthma, cancer, lung illnesses, heart disease, stroke, and other respiratory illnesses.

The health effects of air pollution impact more than just the lungs. Air pollution particles can be small enough to enter the bloodstream. That can cause systemic inflammation that can affect any area of the body.

Economy

The economic impact is staggering. Surpassing 6.1 percent of the global annual gross domestic product, the total economic cost is more than $8 trillion.

These costs stem from a variety of factors. The health-related issues caused by air pollution place a heavy burden on healthcare systems around the world. Pollution-related lost work, school absences, emergency room visits, hospital admissions, medications, and deaths cost $820 billion annually in the United States alone.

Poor air quality impacts the workforce and creates lost productivity. It decreases plant growth, damaging agricultural yields. Loss of tourism where air pollution is high places a strain on local economies.

Environment

Air pollution harms environmental health as well. A variety of air pollutants cause damage to plants and to the larger ecosystems. For example, sulfur dioxide, nitrogen oxides, and ammonia can lead to acidification of soils and water. That can, in turn, lead to weakened ecosystems and losses in biodiversity.

Measuring Air Pollution

The 2022 World Air Quality report was created by IQAir, a Swiss air quality technology company operating the world’s largest free real-time air quality information platform.

Air pollution in this report is measured in terms of the concentration of particulate matter (PM). PM is a mix of solid and liquid droplets suspended in the air.

The report presents PM2.5 air quality data from more than 30,000 monitoring stations around the world. PM2.5 represents particulate matter measured in units of micrograms per cubic meter that are smaller than 2.5 µm in diameter.

These particles are small enough to bore through the lungs, enter the bloodstream, and damage internal organs. In contrast, a human hair is anywhere from 50-70 µm in diameter.

The latest World Health Organization (WHO) Guidelines recommend an annual average of 5 µg/m³ and a 24-hour average of 15 µg/m³ mm for particulate matter smaller than 2.5 µm, or PM2.5. Only six countries met the WHO’s updated health limits: Australia, Estonia, Finland, Grenada, Iceland, and New Zealand.

Africa and Central and South Asian countries suffered from the highest amounts of annual PM2.5 concentrations in 2022. The WHO reports, however, that almost the entire global population, 99 percent, breathes air that exceeds WHO air quality limits.

While it looks like most cities in the world need to make improvements in their air quality, even small differences in concentration amounts of pollutants have a big impact on human health. Let’s take a look at the most dangerous places to breathe in 2022. They amount to the five world capitals with the absolute worst air quality.

Check out IQAir Earth to see a 3-D air quality map in real time.

5. Dhaka, Bangladesh — 65.8 PM2.5

Geography

Dhaka is the capital of Bangladesh, a low-elevation, densely populated country located in the northeastern part of South Asia. It sits south of the Himalayan Mountains bordered by India to the west, north, and east. It shares a small border with Myanmar to the southeast and has a coastline along the Bay of Bengal.

Pollution Ranking

The Air Quality Life Index (AQLI) has ranked Bangladesh as the worst polluted country in the world every year since 2018.

Dhaka, the ninth-largest and seventh-most densely populated city in the world, ranks as the fifth most polluted world capital city. AQLI reports the city’s 22 million residents can expect to lose an average of 7.6 years of life expectancy to the effects of particle pollution.

Sources of Pollution

The sources of the mega city’s air pollution are complex and wide-ranging. Construction is the highest contributor to Dhaka’s pollution at 30 percent of the total. The sprawling metropolis has grown from 50 square kilometers as of 1990 to 300 square kilometers as of 2023, with much of the city developed informally.

Industrial pollution from Dhaka’s 1,000 brick kilns and other factories comes in a close second at 29 percent. Bangladesh’s location on the deltas of several large rivers passing into the Bay of Bengal means there is little natural rock available for construction, creating the need for bricks as the primary building material. Unfortunately, brick kilns have severe negative impacts on air quality.

Vehicle emissions create 15 percent and migrating pollution from neighboring India, Pakistan, and Nepal adds another 10 percent. The remaining pollution comes from activities like burning waste and using wood-fired stoves.

A World Bank report found that sites where major construction and persistent traffic were the greatest in Dhaka had a PM2.5 measurement 150 percent above the WHO guidelines. Incredibly, the World Bank study found that just a 1 percent increase in exposure to PM2.5 above WHO guidelines led to a 12.8 percent rise in the probability of breathing difficulties.

Addressing the Problem

Air quality alone has made Dhaka a dangerous place to live. With levels of particulate pollution 13 times higher than WHO guidelines for clean air, the 22 million people calling the metropolis home welcomed the Bangladeshi government’s National Action Plan in 2020 to reduce air pollution in Dhaka.

The plan includes projects like a metro rail system and designated bike lanes. Government agencies are shifting from using clay bricks that need to be fired to concrete blocks that don’t require firing.

Dhaka still has a long way to go. It’s been three years since the National Action Plan and Bangladesh’s capital city nevertheless ranks fifth for the worst polluted air. There is evidence minor progress is being made, however slow. The city’s 2021 average concentration of particulate matter was 78.1, so there was a 12.3 PM2 drop in 2022.

4. Manama, Bahrain — 66.6 PM2.5

Geography

Manama is the capital of Bahrain, a series of islands situated in a bay on the southwestern coast of the Persian Gulf. The small Arab state is an archipelago consisting of Bahrain Island and 30 smaller islands. Manama, the country’s chief port and capital, is located on the northeastern tip of Bahrain Island.

Pollution Ranking

The AQLI gives Bahrain a pollution ranking of 52 out of 252 countries. It reports that in 2021, the average person in the capital of Manama would have gained one year and two months of life expectancy if fine particulate pollution were reduced to meet the WHO guidelines.

Sources of Pollution

Air pollution in Bahrain comes from fossil fuel-based energy production, waste burning, construction, industrial emissions, private vehicle usage, and the manufacture of fertilizer. Like many countries, though, the capital’s problems are not all man-made.

Sandstorms pose a particular threat to air quality in this desert nation. A series of dust storms in May 2022 inundated countries in the entire West Asian region with massive amounts of particulate matter. These storms instigated negative environmental, social, and health impacts for people living in Manama.

Comparison to 2021

Manama’s rating of 66.6 PM2.5 means its air quality in 2022 was more than 13 times the safe air threshold set by the WHO. Its rating for the previous year was 49.8 PM2. That demonstrates an increase of 16.8 PM2 in the city’s particulate matter concentration from 2021 to 2022. While the sandstorm likely played a role in the high values, Bahrain’s capital still has a lot of work to do to make breathing safe for its residents.

Addressing the Problem

The Kingdom of Bahrain and several major industrial companies located in the country, such as the Gulf Petrochemical Industries Company, have implemented major environmental projects to improve air quality in Manama and beyond. The Bahrain Petroleum Company (Bapco) now removes sulfur from its refinery gas. This process is considered one of the country’s most important environmental projects. Bapco has also installed a treatment system that reduces pollution caused by the process.

Another encouraging result of the country’s initiatives to improve air quality was implemented by the Bahrain National Gas Company. It modified the combustion system in one of the gas turbines resulting in a more than 40 percent reduction in nitrogen oxide levels. The company plans to make similar adjustments to more gas turbines after seeing such promising results.

3. Baghdad, Iraq — 86.7 PM2

Geography

Iraq is one of the easternmost countries of the Arab world sharing a border with Turkey to the north, Iran to the east, Syria and Jordan to the west, and Saudi Arabia and Kuwait to the south. It has a population of 39.6 million.

Known in ancient times as Mesopotamia — the land between two rivers — two significant river systems, the Tigris and Euphrates, flow through Iraq and converge just before consolidating to empty into the Persian Gulf on Iraq’s tiny slice of coast. The Tigris River makes a great oxbow curve through the middle of Iraq’s capital city, Baghdad.

Baghdad is the second-largest city in the Arab world, after Cairo, Egypt. It has a population of over 7 million people living in its hot desert climate. Its average maximum temperature during the summer is 111 degrees Fahrenheit but reached a record temperature of 125.2 degrees Fahrenheit in 2020. Like Manama in Bahrain, Baghdad’s location in the Arab desert makes dust storms a normal occurrence during the summer.

Pollution Ranking

The AQLI gives Iraq a pollution ranking of 25 out of 252 countries. It reports that in 2021, the average person in the capital of Baghdad would have gained one year and eleven months of life expectancy if fine particulate pollution were reduced to meet the WHO guidelines.

IQAir’s World Air Quality Report listed Iraq as one of five of 2022’s most polluted countries.

Sources of Pollution

A study published in IOP Science found that air quality in Iraq has deteriorated in recent years. This dangerous rise in air pollution is due to an increase in the number of electric power plants that work with crude oil, the use of fossil fuels for heating, a rise in public and private transport modes, and the burning of solid waste by uncontrolled methods. Additionally, Baghdad has experienced a decrease in the availability of electricity, which led to the excessive spread of the use of domestic and public generators.

Seasonal dust storms also contribute to Baghdad’s poor air quality. While its desert environment makes this source of pollution unavoidable, Iraq’s vast wetlands were intentionally dried up in the 1990s. This move increased the process of desertification of a once lush river environment.

Comparison to 2021

Baghdad’s rating of 86.7 PM2.5 means its air quality in 2022 was more than 17 times the safe air threshold set by the WHO’s guidelines. This is a huge jump from the fourth-worst capital city of Manama, which averaged 66.6 PM2.5.

Baghdad’s 2021 measurement of 49.7 PM2.5 reflects the severity of the ancient city’s deterioration. In just one year, Baghdad’s residents saw a 37 PM2.5 increase per cubic meter in the air they breathe. It is Iraq’s most polluted city.

Addressing the Problem

Iraq ratified the Paris Climate Accord and has laws restricting pollution. Unfortunately, authorities have done little to curtail large-scale pollution. With few safeguards in place to reduce the extremely pollutive methods used to extract petroleum, Iraq’s oil production nearly doubled from approximately 2.5 million barrels per day (bpd) in 2010 to over 4 million bpd in 2021.

The World Bank ranked Iraq as the second biggest polluter in the world, contributing 10 percent of the global flaring greenhouse emissions. About the same size as California, Iraq has the fifth-largest proven reserves of petroleum on the planet as well as substantial reserves of natural gas.

The controversial practice known as flaring involves burning off the excess natural gas during oil extraction. While the government stalls on taking action, local nongovernmental organizations have taken up the call to end the country’s reliance on flaring. Groups such as Nature Iraq and Waterkeepers Iraq are working to restrict the region’s pollution-causing practices.

Local activists and civil society organizations are taking the lead in addressing the crisis by planting trees, preserving river water, and raising awareness of the effects of pollutants on human health. Their efforts are a breath of fresh air for the residents of a country struggling with so many environmental obstacles.

2. New Delhi, India — 89.1 PM2.5

Geography

India is a peninsula that occupies the greater part of South Asia. It shares a border with six countries — Pakistan to the northwest, China, Bhutan, and Nepal to the north, and Myanmar and Bangladesh to the east. With roughly one-sixth of the world’s population, 1.3 billion, India has the second-highest population after China.

India’s capital city of New Delhi is also one of the most populous and cosmopolitan cities in the world with a population of more than 11 million. New Delhi is located in Northern India and features a dry winter, humid subtropical climate. The Yamuna River runs through the city creating about 12 acres of wetlands.

New Delhi sits within a greater region known as the National Capital Territory (NCT), or just Delhi. This area is home to close to 35 million people.

Pollution Ranking

The AQLI gives India a pollution ranking of 2 out of 252 countries. It reports that in 2021, the average person in the capital of New Delhi would have gained 5.26 years of life expectancy if fine particulate pollution were reduced to meet the WHO guidelines.

In 2022, 12 of the 15 most polluted countries in Central and South Asia were in India, according to the IQAir report. In November of 2022, Delhi reached an incredible high of 176.8 PM2.5. Residents of New Delhi spent 66.3 percent of the year breathing air that was more than 10 times the WHO guidelines for safe air.

Sources of Pollution

Multiple sources produce the dangerous numbers of PM2.5 seen on record in India’s capital city.

New Delhi has experienced large-scale expansion in its service sector as it is one of the biggest commercial and economic powerhouses of India and home to many multinational companies. While this is good news for the capital’s economy, more people mean rising vehicular emissions.

The fumes emanating from vehicles are a significant contributor to air pollution levels in New Delhi. Other sources include burning waste, wood for cooking, crop stubble and farmland, and ceremonial firecrackers. Factories, power plants, and industrial zones also add large quantities of smog and haze to the air.

Comparison to 2021

In early 2021, New Delhi’s PM2.5 levels went as high as 339.5 μg/m³, a number as shocking as it is dangerous.

IQAir doesn’t report numbers in New Delhi for previous years, but greater Delhi’s (NCT) 2021 particulate matter number was 96.4 PM2.5. The most recent data from 2022 shows a level of 92.6 PM2.5. Even a small drop in pollution levels is a step in the right direction.

Addressing the Problem

The city has been working to improve the city’s air quality by reducing vehicle emissions and banning coal.

Most recently, India’s government initiated a plan known as the Graded Response Action Plan in New Delhi-NCR to combat pollution during the winter season. The plan directs authorities in the capital to enforce a ban on coal usage in hotels and restaurants. It also mandates the city’s government to take punitive measures against polluting industries when the air quality in Delhi plunges below the “poor” category.

1. N’Djamena, Chad — 89.7 PM2.5

Geography

Chad is a landlocked country in north-central Africa with much of its northern territory situated in the Sahara Desert. It shares a boundary with Libya in the north, Sudan in the east, the Central African Republic in the south, and on the west by Cameroon, Nigeria, and Niger.

Although Chad is the fifth largest country in Africa, it has a population density of only about 20 persons per square mile. Chad’s population is around 18 million. Its capital city of N’Djamena is home to just under one million people.

N’Djamena is situated in the central semiarid tropical (Sahel) zone and gets between 12 and 32 inches of rain between every June and September.

Pollution Ranking

Chad topped the list of IQAir’s most polluted countries between 2018 and 2022. While it is the only African country in the top five most polluted countries, air monitoring on the continent is sparse.

IQAir’s report only includes data from 52 cities and 156 stations in the region. NASA satellite data reveals that 70 percent of the world’s wildfires occur in Africa. This means that the limited availability of air quality data on the continent is the most important issue in addressing air pollution.

Sources of Pollution

Dramatic increases in particulate matter seen in January and March can be partially attributed to massive dust storms from the Sahara Desert. Exposure to particulate matter from dust emissions accounts for up to 40 percent of the total number of infant deaths in Africa.

Chad is particularly affected by dust storms because of its geography. The Bodélé Depression, the lowest point in the country, is the largest source of dust emissions in the world.

The use of biomass fuels and traditional stoves for cooking is an additional factor in Chad’s abysmal air quality. Combustion of those fuels causes harmful levels of indoor air pollution that spreads into surrounding communities. Uncontrolled waste burning, aging vehicle emissions, meatpacking industries, and the oil industry are all contributing factors in the deterioration of air quality in N’Djamena.

Comparison to 2021

Air quality in Chad worsened in 2022 as PM2.5 concentrations increased 18 percent from 75.9 μg/m3 in 2021 to 89.7 μg/m3. In March of 2022, air quality hit hazardous levels when the PM2.5 concentration was recorded at 245.6 μg/m3.

Residents of N’Djamena spent 47.3 percent of the year breathing hazardous air that was more than 10 times the WHO guidelines. The air in Chad’s capital city deteriorated from 2021 levels of 77.6 μg/m3 to 89.7 μg/m3 in 2022.

Addressing the Problem

Studies show that Chad lacks policies and governance to control air pollution. Despite this, the United Nations (UN) helped the country implement household waste management services in some communities and refugee sites.

Opportunities for improvement abound, though. Supporting power generation, making electricity more affordable to limit the cutting of firewood, which is exacerbating desertification and pollution, and establishing waste treatment plants are all areas addressed by the UN’s National Poverty Reduction Strategy.

It is possible to improve the air quality in N’Djamena, just like in any other city. IQAir’s report includes many cities and countries that have successfully implemented strategies similar to those being suggested in N’Djamena. These improvements offer hope for all the world capitals on our list.

Quick Guide to Comparing the 5 World Cities with the Absolute Worst Air Quality