Similar initiatives have been launched from Barcelona to Bogotá, but they have misinformation, political pressure and vested interests stacked against them
Ten years ago, Alastair Harper was an advocate for young people’s health sitting in a stuffy meeting room in London planning an air pollution campaign. “My phone started buzzing,” he said. “I took the call, and then told the room I needed to leave immediately.
“I had to get to UCLH [one of London’s major hospitals]. My own child was headed there in a blue-lit ambulance because she was struggling to breathe London’s toxic air.”
Hundreds of thousands of parents across the UK capital had similar experiences in those years. Between about 6,000 and 8,000 people were dying prematurely each year in London in the late 2010s. In 2020, an inquest found that the death of Ella Adoo-Kissi-Debrah in 2013 had been a direct result of air pollution, the first time it had been listed as a cause of death in the UK.
This week, a study from Queen Mary University London (QMUL) showed a significant reversal. Children’s lungs had grown bigger and stronger since the most polluting vehicles have been restricted on the capital’s roads, scientists found. The ultra-low emission zone (Ulez) – introduced by London’s mayor Sadiq Khan in 2019 and expanded in 2021 and 2023 – charges £12.50 a day for more polluting vehicles that do not meet stringent standards. It has drastically cut levels of nitrogen dioxide, a harmful pollutant.
To Harper, who later worked for Khan as an environmental adviser, and now works independently, relief at his own child’s recovery has been supplemented by the satisfaction of knowing that far fewer parents will experience such dread. “To know now that same air is so much safer for the kids that breathe it because of the political choice of one man makes me feel proud of this city,” he said.
Nick Hopkinson, a professor of respiratory medicine at Imperial College London, said the QMUL study was not a surprise. “There is an absolute wealth of evidence that air pollution is a major cause of ill health and premature death across the planet,” he said. Air pollution kills 7 million people a year globally, according to the World Health Organization.
Poor air not only causes respiratory difficulties and the stunting of children’s lungs, but also heart disease and stroke. It is associated with some forms of cancer, dementia, autism and cognitive difficulties in children too. New studies are adding to our knowledge, but we have known for decades of the basic dangers of dirty air. So why is there so much opposition to curbs on air pollution, which are clearly sound public health measures?
This opposition, culture war even, is central for all cities hoping to follow Khan’s lead. The leading causes of air pollution vary around the world – coal use in power stations in China and India, agricultural burning in south-east Asia, waste burning in many of the poorest countries and dust and local industry in others – but road traffic is a constant.
The technology to cut all of these types of air pollution already exists, says a former social development minister of Ecuador and now executive director of the Breathe Cities initiative, whose supporters include the Clean Air Fund and C40, a global coalition of mayors and leaders of nearly 100 major cities. “We know that we have the means to make a difference, and we are sharing knowledge and success stories so they can be replicated with impactful policies,” she said.
In the case of coal, the alternatives are renewable energy. Halting the burning of forests and peatlands would also combat the climate crisis. The alternatives to polluting traffic are public transport, electric vehicles, the redesign of cities and encouragement of active transport – walking and cycling. Trees are also important everywhere.
Paris and Barcelona have shown what is possible within a few years when mayors embrace the joys of cycling, following the lead long ago taken in Denmark and the Netherlands. New York’s Zohran Mamdani, now wearing a cycle helmet, hopes to do the same. But elsewhere in car-dominated America, infamously poor public transport provision, an intractable SUV culture and a president in Donald Trump intent on rolling back environmental protections mean widespread change is unlikely.
Other cities are working to make a difference. Bogotá is about to embark on its second Zuma, a clean air zone that involves expanding cycle lanes and footpaths, paving roads to suppress dust and planting trees. The Colombian capital won last year’s global Earthshot prize for its first Zuma. The city’s environment secretary, Adriana Soto, said: “Residents helped shape the design, particularly how the works would maintain access to their homes and respond to local mobility needs.” Hundreds of cities around the world now have clean air zones of varying sizes.
Another is Kenya’s capital, Nairobi, which passed an air quality act in 2022 that requires harmful emissions to be halved by 2035 and has installed a network of 50 low-cost monitoring stations as a first step. Imports of vehicles more than eight years old are banned, and the city is consulting on establishing clean air zones. The lead for the C40 Breathe Cities project in Nairobi, Victor Indasi, said: “More remains to be done, but Nairobi is firmly on the right trajectory.”
Bulgaria’s capital, Sofia, is saddled with old-fashioned heating systems dependent on coal and wood burning. These are being phased out and replaced with cleaner heat pumps, subsidised for those on low incomes, as part of a city-wide introduction – the first in south-east Europe – of low-emissions zones for transport and heating. Recent results show a 22% reduction in the average concentration of PM10 particulate matter, and a halving of days that exceed air quality guidance levels. Poland is also cutting its reliance on solid fuels.