Top 5 major cities with good air quality in 2024

The 2024 World Air Quality Report provides a revealing snapshot of global pollution—and the progress being made. While many urban areas continue to struggle, several major cities are proving that clean air and dense populations can coexist.

The five cities highlighted here have set a remarkable standard, maintaining annual average PM2.5 levels at or below the World Health Organization’s (WHO) strict guideline of 5 µg/m3 or less. PM2.5—one of the most harmful air pollutants—is a key measure of air quality due to its severe health effects.

Beyond these major urban centers, many smaller communities have also achieved commendable air quality – and that’s good news as well. However, this list focuses on large, well-known cities, proving that even the world’s most populous areas can breathe clean air.

5. Tied: Vancouver, Canada

The fourth and fifth cleanest major cities in the world recorded the same annual average PM2.5 concentration in 2024.

Air quality in Vancouver, British Columbia was much better than in previous years, allowing the city to meet the WHO guideline for the first time. Vancouver’s annual average PM2.5 concentration in 2024 was 4.2 µg/m3; the city’s 2023 annual average had been 5.5 µg/m3. 

Although Canada experienced a significant and highly destructive 2024 wildfire season, it was less severe than the historic 2023 season (1). Some hazy days returned to the city in August due to fires in British Columbia and neighboring Washington State, but the city was still able to experience 9 out of 12 months in 2024 with average monthly PM2.5 concentrations under 5 µg/m3 (2).

Vancouver has set a goal of reducing carbon pollution by 50% by 2030 and becoming carbon neutral by 2050 (3). City policy considers land-use planning, encourages zero emissions vehicles and buildings, promotes increasing greenspaces, and takes into account environmental justice – the inequal, unfair distribution of pollution exposure and its health effects on at-risk populations.

Air quality in Vancouver, Canada on March 20, 2025. Source: IQAir Map.

4. Tied: San Francisco, USA

Air quality in San Francisco, California also met the WHO guideline in 2024. The annual average PM2.5 concentration in the city was 4.2 µg/m3, an improvement over the 2023 annual average of 5.8 µg/m3. 

San Francisco was able to experience air quality within the WHO guideline 11 out of 12 months of that year. The city’s average PM2.5 concentration in December was 10.3, likely due to light winds blowing in agricultural pollution from California’s Central Valley (4). Other sources of poor air quality in winter months can include vehicle pollution, wood burning, and temperature inversions.

Like Vancouver, San Francisco benefits from its coastal location. Frequent rainy days can help reduce air pollution. The city pursues smart environmental policies by encouraging electric vehicles, replacing gas-burning stoves, investing in clean mass transportation, and by enacting an all-electric construction ordinance (5). San Francisco has a stated goal of cutting the city’s emissions by 61% below 1990 levels and of reaching carbon neutrality by 2040.

Air quality in San Francisco, USA on March 24, 2025. Source: IQAir Map.

3. Seattle, USA

In 2024, Seattle, Washington measured an annual average PM2.5 concentration of 4.1 µg/m3 – the city’s first time meeting the WHO guideline since 2017.

Seattle’s best air quality month in 2024 was April, with an average monthly PM2.5 concentration of 2.9 µg/m3. The city’s worst month was in August at 5.6 µg/m3 due to regional wildfire smoke (6). Smoke, fossil fuel emissions, and industrial activity can all worsen air quality in Seattle (7). Extreme heat has recently become more common in the region, and heat waves can worsen air quality. Between 2020 to 2023, Seattle experienced between 42 and 45 days over 80 degrees Fahrenheit. However, there were only 35 such days in 2024 (8).

Overlooking Puget Sound near the Pacific Ocean, Seattle benefits from the same ocean breezes enjoyed by Vancouver and San Francisco. Some policies and ordinances may be helping as well – at the end of 2023, Seattle passed an emissions standard law requiring decreased building energy use (9). In 2024, Washington State’s Department of Ecology also launched a $10 million grant program intended to fund local underserved communities’ efforts to counter air pollution (10). Though award notification didn’t begin until early winter 2024 and likely didn’t affect the year’s air quality data outcome, it’s a move that may help sustain Seattle’s positive air quality gains.

Air quality in Seattle, USA on March 20, 2025. Source: IQAir Map.

2. Canberra, Australia

Canberra, Australia’s annual average PM2.5 concentration for 2024 was 3.9 µg/m3.

Australia’s annual average PM2.5 concentration was 4.5 µg/m3. Since Canberra is the nation’s capital, both Australia and its capital were within the WHO air quality guideline. It also means that Australia is meeting its own outdoor air quality stand of an annual average PM2.5 concentration of 8 µg/m3 (11). Canberra edged out both Sydney and Melbourne, Australia in 2024, both of whom were among the top five cleanest cities in 2023. 

Unlike the other four cities on this list, Canberra doesn’t lie on the Pacific Coast. However, it is only about 65 kilometers inland from the Pacific, an important source of pollutant-dispersing ocean breezes. 

The city is not without air quality challenges. Australia can experience severe bushfires in the summer. Bushfire smoke can reach Canberra and severely impact air quality; the city maintains a strategy for combatting all sources of smoke by providing assistance for people impacted by bushfire smoke, improving air quality monitoring and forecasts, and bolstering wood heater emission standards (12)(13).

Air quality in Canberra, Australia on March 20, 2025. Source: IQAir Map.

1. Auckland, New Zealand

In 2024, Auckland, New Zealand, stood out as the major city with the cleanest air by recording an annual average PM2.5 concentration of just 3.3 µg/m3. 

New Zealand had annual average PM2.5 concentration was 4.5 µg/m3 in 2024. It was the 10th least polluted country or territory in the world. 

New Zealand's geographical advantages play a key role in its clean air. The nation’s islands benefit from coastal winds that push local pollutants out to sea, while its isolation from neighboring countries helps reduce the intrusion of transboundary pollution. Additionally, the country experiences significant rainfall, which aids in dispersing airborne contaminants.

New Zealand has generally improved on its air quality over the years, gradually decreasing from an annual average air quality 7.7 µg/m3 in 2018. However, while still under the WHO guideline, the country’s annual average PM2.5 of 4.4 µg/m3 is a little higher than its annual average of 4.3 µg/m3 in 2023. 

In fact, both Auckland and New Zealand’s clean air status may be at some risk in coming years. The government has opted to encourage mining, reverse a ban on oil and gas exploration, and is at risk of failing to reduce methane emissions (14). And citing the cost of cleaner fuel, the national air carrier, Air New Zealand, has dropped its 2030 emissions target.

Air quality in Auckland, New Zealand on March 20, 2025. Source: IQAir Map.

The takeaway

Even in these clean air cities, don’t forget: no amount of air pollution is entirely safe. Sustained action is essential to reduce poor air quality, maintain pollution reduction progress, and safeguard public health. Monitoring air quality where we live, work, and attend school can also help keep us air aware and reduce exposure to pollutants.

No matter where we live, we can all play a role in creating a cleaner, healthier future—by advocating for cleaner energy, supporting strong environmental policies, and contributing to air quality monitoring.