It’s in the Air: Clean air zones are improving public health and ending our dependence on fossil fuels

To tackle air pollution and the climate crisis, we must end our reliance on fossil fuels and accelerate the shift to zero-emission technologies.

This means rethinking how we travel.

Across the globe, over 30 C40 cities – including Bogotá, London, Paris, Quito, Seattle and Stockholm – are working to create clean air zones, one of the most impactful transport policies to rapidly deliver emissions savings and other benefits. These cities are just the beginning; together, they’re passing the baton to each other as we move towards a future where every city enjoys the benefits of clean air.

What are clean air zones?

They are areas in a city with measures to cut toxic pollution from vehicles, promote active travel like walking, cycling and public transport, and prioritise people over cars.

These zones give residents and families more space to breathe, walk, play, experience nature and connect.

Backed by data

Clean air zone policies are not easy to implement and often encounter resistance and opposition in many forms. Yet, when designed effectively and equitably, they have proven to be transformative and successful.

The recent expansion of London’s clean air zone – now the world’s largest – has led to a 13% reduction in nitric oxide emissions (NOx) from cars and a 7% reduction from vans, cutting total NOx emissions by 424 tonnes; a 22% decrease in fine particulate pollutants (PM2.5) emissions from cars.

London is significantly reducing air pollution and protecting the health of Londoners, inspiring many other cities to join the movement. Cleaning up the air we breathe takes courage and bold action.

‘It’s in the Air’

Since July 2024, cities at the forefront of this movement have participated in C40’s 'It’s in the Air' campaign. Launched in Paris by Mayor Anne Hidalgo, the global marathon highlighted the importance of clean air zones to improve the health and lives of residents. This initiative inspired local and global activities.

Mayor of Paris, Anne Hidalgo, said: “Paris’s collaboration with C40 mayors ahead of the Olympics demonstrated how cities can pass the baton to each other, join forces to combat the climate crisis and celebrate open, healthier, more liveable streets for everyone.”

The campaign ran for eight weeks up until International Day of Clean Air for Blue Skies, when cities were joined by dozens of partners, youth leaders and other key stakeholders in celebrating the important work they’ve been doing to transform streets and public transport, improve air quality and people’s health and wellbeing.

Over 10,000 city residents from four regions engaged with on-the-ground community activities, air quality workshops and #ItsInTheAir creative events and installations during the marathon. The campaign organically reached over five million impressions online through over 700 multimedia content and social media posts. Its goals were to keep up the drumbeat on the campaign’s vision, amplify on-the-ground activities, share stories from local communities, provide information, and bust common myths about clean air zones.

What happened on the ground in the frontrunner cities?

• Bogotá engaged over 3,000 residents, visitors and cyclists in an interactive workshop on clean air, ZUMAs (Zonas Urbanas por un Mejor Aire) and artistic performances during the traditional el mes de las cometas;
• Johannesburg hosted community-led activities, including tree planting at schools, educational workshops and celebrated joining the Breathe Cities programme;
• Quito welcomed over 4,000 families and cyclists to a car-free Historic Centre filled with music, art installations and sensory experiences, reinforcing the city’s commitment to climate action and its sustainable mobility plans;
• Seattle organised a weekend of street closures, sports events and street markets involving local communities through our It’s in the Air map designed to show how residents can get around the city without relying on cars;
• Stockholm attracted hundreds of visitors – including Mayor Wang?ard – to Norrmalmstorg Square for breathwork, yoga, lung testing and clean air visualisation games, engaging residents in air quality discussions ahead of the launch of the world’s first near-zero emissions zone.

People want to see clean air zones expand

Recent C40 polling results show overwhelming support for transforming streets and public spaces among city residents in Bogotá, Johannesburg, London, Quito, Seattle, Seoul, Stockholm, and Warsaw. Key findings include:

• Over 80% of respondents want their leaders to prioritise clean air, with 98% in Bogotá;
• More than 90% support expanding public transport and active mobility;
• 88% favour creating or expanding clean air zones, with approval rates of 97% in Johannesburg and 96% in Quito.

As part of C40’s work celebrating zero-emission areas, the 'It’s In The Air' campaign highlighted the need for transformative transport policies, offering a platform to local communities and global partners to come together, asking for change, and creating healthier cities.

The marathon continues — and everyone has a role to play.

At C40, we recently produced the clean air toolbox, which serves as a comprehensive guide designed to help cities design and implement clean air zones, engage with residents and gain public and political support on stepping stone policies.

The toolbox provides essential knowledge, technical guidance, best practices and case studies from cities worldwide. It is designed for city staff, campaigners, communications experts, politicians and civil society partners who are developing or supporting clean air zone policies.

Learn how to build a clean air zone in your city and download the toolbox – now available in English, French, Portuguese and Spanish.