Cleaner air today, reduced emissions tomorrow: Barcelona’s low-emissions zone.

As a place with a lot of industrial activity, high traffic volumes, infrequent rainfall and the occasional Saharan dust cloud blown in on the wind, the city of Barcelona on the northeast coast of Spain can sometimes experience poor air quality.

As a place with a lot of industrial activity, high traffic volumes, infrequent rainfall, and the occasional Saharan dust cloud, the city of Barcelona on the northeast coast of Spain can sometimes experience poor air quality. To address this, the metropolitan council set up in 2020 a network of 11 monitoring stations that continuously measure concentrations of contaminants in the air.

Polluted air has a very negative impact on human health. In Barcelona’s air, the two most damaging elements are Nitrogen Dioxide (NO2) and particles smaller than 10 micrometers (PM10). NO2, which should not be confused with the greenhouse gas Nitrous Oxide (N2O), is a gas primarily emitted from vehicle exhaust fumes. It irritates the lungs, potentially causing long-term damage. Alongside this, tiny particles are released into the air from fires, the friction of vehicles driving on the road, construction works, and the occasional desert sand. These particles can affect both the respiratory and circulatory systems. When their levels are high, they exacerbate the symptoms of anyone with heart or lung problems, or conditions like asthma.

In response to these challenges, the city of Barcelona came up with several solutions aimed at improving air quality, in line with World Health Organization (WHO) recommendations and European Union (EU) commitments. The 2019 plan to reduce atmospheric contamination includes 25 structural measures and 58 actions. One of these measures is the implementation of the ‘low-emissions zone’ (ZBE), which fully came into force in January 2020. The ZBE covers 95 km² of the metropolitan area and operates during working hours, from Monday to Friday, between 07:00 and 20:00. The zone is accessible only to vehicles approved by the transit authority, with these vehicles categorized according to their level of contaminating emissions. On days when air quality is poor, the most polluting vehicles may be prohibited from entering. Visiting vehicles, including those registered abroad, must apply for temporary permission to enter the zone.

This initiative is based on a concept from behavioral psychology called a ‘nudge’—by making it inconvenient to drive highly polluting vehicles, the city encourages residents and visitors to choose cleaner alternatives. There are many alternatives to driving: cheap, frequent, low-emission, and well-connected public transport; 200 km of cycle lanes; and pedestrian-friendly streets. Additionally, those who choose to dispose of their old polluting car are offered three years of free public transport. This approach is both excellent and necessary. When I first moved to Barcelona, I found the traffic absolutely overwhelming. While I don’t think it has decreased that much, the quality of public transport has significantly improved, and there are additional projects in place to make the urban environment even more pleasant.

While the immediate goal of improving air quality is to protect public health, reducing air pollution—especially from vehicle emissions—is also a crucial strategy in mitigating the accelerating pace of global warming. Transportation, which includes the movement of people, food, and goods, is one of the largest consumers of fossil fuels. Project Drawdown emphasizes that the transition to cleaner alternatives, increasing efficiency, and electrifying transportation are essential to curbing emissions in this sector. This shift is urgent: in 2019, transport accounted for nearly a quarter of the EU’s total CO2 emissions, with road transport responsible for 71.7% of that figure. Reducing these emissions is vital for reaching the EU’s target of climate neutrality by 2050. Barcelona’s low-emissions zone is a key component of the city's broader strategy to combat climate change. As more cities adopt similar measures, we can look forward to not only cleaner air but also a more sustainable urban future, where both public health and the planet are prioritized.