Why public transport is vital in achieving clean air for blue skies

Over 99 percent of people breathe unsafe air, leading to 6.7 million deaths every year. On the International Day of Clean Air for blue skies the UN Environmental Programme (UNEP) calls on everyone to come together for clean air. And to achieve clean air in cities, public transport is key.

According to the World Health Organisation (WHO) the health risks associated with particulate matter equal to, or smaller than 10 microns (PM₁₀) are particularly high. They penetrate deep into the lungs. Particulate matter smaller than 2.5 microns can even enter the bloodstream. This has severe impacts on cardiovascular and raspatory health.

This size of particulate matter (PM) is primarily generated by fuel combustion, for example in transport, energy and industry. Tackling air pollution by decreasing our reliance on fossil fuels also tackles that other environmental threat to human health: climate change.

Back in June, Maria Neira of the WHO joined us at the annual UITP Public Transport Summit to remind us of how public transport makes our cities and our lives happier and healthier. She shared her views on how public transport is critical to improve public health, especially with regard to air quality.

“Pollution is killing us. A suitable transport system is a critical part of public health. It reduces air pollution, it reduces road traffic deaths, it reduces non-communicable diseases.”

She called on ministers and mayors across the world to have two things on their desk. One is a copy of the WHO report on combating air pollution. The second and most important: a current measurement of the air quality in their cities. “Start by looking at that every day, and make policies that will help improve that number. This is the only way to make our planet, and our citizens healthier.”

Public transport emits significantly less than private vehicles. Doubling public transport usage by 2030 would not only create tens of millions of jobs and cut urban emissions in half, it would also reduce air pollution from transport by up to 45%.

To achieve this, investments are needed. Not only should we decarbonise existing public transport, but we should give more people access.

According to the United Nations Statistics Division 50% of the world’s urban population doesn’t have convenient access to public transportation. This means that 1 in 2 people don’t have a bus or tram stop within 500 meters walking distance, or a train, subway or ferry stop within 1,000 meters.

A 2023 study “Subways and CO2 emissions: A global analysis with satellite data” uses satellite data to measure CO2 emissions in urban areas around the world. Researchers Susmita Dasgupta, Somik Lall and David Wheeler found that metros cut population related CO2 emissions in half.

Even under pessimistic assumptions on investment cost for implementing metros, the researchers find that “hundreds of cities realise a significant climate co-benefit, along with benefits from reduced traffic congestion and local air pollution.”

Public transport is the best solution to decarbonise cities, fast-tracking the energy transition and slashing emissions before 2030. It is the most cost-efficient way to decarbonise people’s daily mobility and clean up our skies. The investments pay for themselves.

To get there, we need to decarbonise our vehicle fleets while growing the supply of renewable energy. At the same time, governments should support citizens in shifting from the private car to public transport, walking and cycling.

By supporting national governments and the local level to make these investments we can build better urban mobility systems from the ground up. This is the only way to strengthen public transport and active mobility, and raise the level of ambition we need so urgently.