9 October 2026
Blog Global

How Clean Air Zones Are Breathing New Life Into Neighbourhoods

Whether operating across an entire city or targeted at specific neighbourhoods, Clean Air Zones allow local governments to focus resources where they are needed most. Across the Breathe Cities initiative, cities are scaling, accelerating and redefining these zones to deliver tangible, street-level progress on cleaner air that residents can see and feel.

A Clean Air Zone is a designated area where a city implements targeted measures to reduce air pollution, control emissions and protect public health. Originally, most Clean Air Zones focused primarily on vehicle access, limiting which vehicles could enter certain areas based on their emissions. 

Today, the most ambitious zones take a broader approach, bringing together action across multiple sectors to tackle pollution as a whole. By coordinating investments in greener spaces, clean heating, active mobility infrastructure (such as bike lanes) and emissions controls, cities can transform highly polluted neighbourhoods into safer, more resilient public spaces. Combining these measures allows local governments to maximise their impact and directly reduce exposure for the residents who need it most.

Clean Air Zones are also known by different names in different cities: London’s Ultra Low Emission Zone (ULEZ), Bogotá’s Zonas Urbanas de Mejor Aire (ZUMA) and Jakarta’s Kawasan Rendah Emisi (KRE-T) are examples. But all share the same goal: reducing residents’ exposure to air pollution and making cities healthier places to live.

Highlights

Clean Air Zones bring together a set of coordinated measures, from shifting to cleaner, more accessible public transport to promoting active travel, to reduce residents' exposure to toxic air pollution and improve quality of life.
Cities are focusing their Clean Air Zones implementation efforts in the neighbourhoods most affected by air pollution, so that action reaches the communities carrying the heaviest health burden first.
By drawing on local air quality data and engaging directly with residents, cities can design interventions that directly respond to each communities’ unique needs.

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Red double-decker buses driving through a London Clean Air Zone street.

Building the world’s largest Clean Air Zone

London’s Clean Air Zone has established a global blueprint for urban clean air policy, improving the air that more than 9 million residents breathe every day. Under the leadership of Mayor Sadiq Khan, London met the UK’s legal nitrogen dioxide (NO2) limits for the first time, reaching clean air targets nearly 200 years ahead of original projections. Today, roadside NO2 levels are:

  • 54% lower in central London, 
  • 29% lower in inner London and 
  • 24% lower in outer London.

London

Since the introduction of the Clean Air Zone vehicle compliance across the capital has surged from 37% to nearly 97%.

To support drivers through the transition, the city delivered a Mayor-funded scrappage scheme, while net revenue generated from non-compliant vehicles is directly reinvested into public transport upgrades, such as the new Superloop bus network, expanding clean travel options across outer London.

These air quality gains are translating directly into public health benefits across the capital. Estimated deaths linked to air pollution fell by around 40% between 2019 and 2024, while a recent landmark study found that air improvements since ULEZ was introduced helped accelerate children’s lung growth, contributing to a reduction in the proportion of children with clinically impaired lung function from 14% to 9% in London. By proving that bold urban action can deliver immediate health gains, London offers a roadmap for cities worldwide looking to transform the air their residents breathe.

Scaling local action through Urban Zones for Better Air (ZUMA)

Bogotá’s ZUMA (Zonas Urbanas de Mejor Aire – Urban Zones for Better Air) model shows how cities can treat clean air as a shared responsibility. By bringing together the environment, mobility, health and planning secretariats, the city concentrates its resources to tackle air pollution directly in the vulnerable communities that face the highest risks.

Bogotá

Proving the model in Bosa-Apogeo (ZUMA 1): In the city’s first zone, Bosa-Apogeo, community surveys revealed that 15% of residents suffered from respiratory illnesses, and local roads were frequently used as bypasses to avoid heavy traffic. As a first step toward reducing residents’ exposure to pollution, Bogotá improved 3,860 square metres of roads, planted 431 trees, strengthened 31 community gardens, and conducted 150 mobile enforcement operations to curb vehicle emissions. Alongside these physical interventions, the city installed 11 air quality microsensors to track local data and monitor progress.

Scaling to Ciudad Bolívar (ZUMA 2): Bogotá officially established its second ZUMA in Ciudad Bolívar-Ismael Perdomo in August 2026. Spanning a 2.95 km² area, this new zone will directly benefit over 97,600 residents across 15 neighbourhoods. Implementation began immediately with native tree planting, road maintenance to suppress dust, and the creation of a large-scale mural to promote community awareness and engagement with these measures. To track air pollution in real time, the city installed the area’s first air quality microsensor, part of a broader Breathe Cities-supported rollout of 40 sensors across Bogotá.
Panoramic view of a street in Sofia, Bulgaria, featuring local urban traffic, historical buildings, and mountains in the background.

Delivering Southeast Europe’s first dual-sector Low Emission Zone and supporting residents in their transition to healthier homes

Sofia is the first city in Southeast Europe to introduce low-emission zones (LEZs) covering both road transport and residential heating, and data shows they are helping residents to breathe healthier. 

The city used a phased approach to introduce the measures to give residents time to adapt. The LEZ was first introduced in the city centre in 2023 before expanding outward and adding new vehicle categories in 2025. It currently operates during the winter months, a high-risk time for air pollution as winter humidity can trap pollutants close to the ground.

Sofia

High-angle aerial view of cars, taxis, and pedestrians navigating a busy street intersection in Sofia, Bulgaria.

The transport zone has delivered immediate health benefits:

  • Reducing winter nitrogen dioxide levels by 10%, curbing toxic traffic fumes and protecting respiratory health.
  • Decreasing daily entries of the most polluting vehicles from 20,000 to roughly 2,000, lowering street-level exposure to exhaust fumes.
  • Meeting EU clean air standards for fine particles for three consecutive years, meaning the pollutants that cause health impacts like lung disease and heart conditions are at their lowest levels in the city’s recent history.
An elderly woman standing in her home next to a modern, clean heating system replacement in Sofia, Bulgaria.

The city also targets domestic heating, one of the primary sources of harmful particles (PM2.5) during winter.

This is a widespread challenge across Central and Eastern Europe, where many households still rely on ageing, polluting boilers and solid fuel heating. To support residents through the shift, Sofia covers 100% of appliance replacement costs. So far, the city has helped more than 11,000 households transition to cleaner alternatives and prevented an estimated 219 tonnes of emissions annually.

Building on this progress, in October 2026, the Mayor of Sofia announced his ambition to extend the transport LEZ into a year-round model during Clean Air Week Sofia, in a series of events supported by Breathe Cities.

Where to look for further guidance on Clean Air Zones 

  • This Clean Air Zone Toolbox provides resources and examples from cities worldwide, to support cities in implementing fair and inclusive Clean Air Zones that have broad support. 
  • Clean Air Zones: Practical guidance for cities aims to help city officials navigate the pathways towards a Clean Air Zone, whichever stage of the process they are at.

FAQ

Frequently Asked Questions

What is a Clean Air Zone?

A Clean Air Zone is a defined area of a city where targeted measures are introduced to reduce air pollution and protect public health. Clean Air Zones allow cities to focus interventions where they can have the greatest impact. These can include cleaner transport, construction, and heating, or urban greening and other measures that address major sources of air pollution.

How do Clean Air Zones differ from Low Emission Zones?

Clean Air Zones are referred to by different names in different cities: London’s Ultra Low Emission Zone (ULEZ), Bogotá’s Zonas Urbanas de Mejor Aire (ZUMA) and Jakarta’s Kawasan Rendah Emisi (KRE-T) are all examples. The measures involved vary too, but all share the same goal of reducing residents’ exposure to air pollution and making cities healthier places to live.

Low Emission Zones are one example of a Clean Air Zone. Many European cities introduced them as an early approach, focusing on restricting the most polluting vehicles from entering a defined area. Today, cities are increasingly taking a more holistic view, combining vehicle measures with urban greening, clean heating and active travel infrastructure to tackle pollution from multiple sources at once.

Why do cities need Clean Air Zones?

Clean Air Zones help cities to reduce air pollution and protect public health in areas where people face high levels of exposure. By focusing action within a defined area, cities can bring together measures that tackle multiple sources of pollution and respond to local conditions. Clean Air Zones can also help cities turn broader clean air commitments into targeted, measurable action that improves the places where people live, work and spend time.

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