Barcelona is the most congested city in the State. In 2022, it once again registered the highest travel time in the city center and the metropolitan area. Road traffic is the main source of greenhouse gas emissions. It is also the main contributor to nitrogen oxide (NOx) emissions and the second to suspended particulate matter (PM10 and PM2.5).
Continuing to exceed emission levels could lead to an economic sanction by the Court of Justice of the European Union (CJEU). In fact, the community institution condemned Spain last year for "failing to fulfill its obligations [...] by not having ensured that the annual limit value set" in the urban areas of Madrid, Barcelona and Vallès-Baix Llobregat "was not systematically and continuously exceeded". The NO2 limit values in the Barcelona Metropolitan Area (AMB) have been infringed since the Directive came into force in 2010.
Traffic-related air pollution has negative effects on respiratory health (asthma, allergic rhinitis, chronic obstructive pulmonary disease, lung cancer), cardiovascular (hypertension, coronary heart disease, myocardial infarction, heart failure), obstetric (fetal growth restriction, preeclampsia, premature birth, low birth weight), neurocognitive (lower cognitive development, slower brain maturation, memory and concentration problems) and psychological (common mental disorders), in addition to an increase in mortality. Thus, reducing the average annual levels of NO2 and PM2.5 to the limits proposed by the European Commission would prevent 525 cases of childhood asthma, 110 lung cancers and 1,000 deaths in Barcelona each year (ASPB, 2020).
Congestion also reduces the economic growth of the metropolis (productivity, investments, employment, etc.). Pollution linked to urban transport in Barcelona represented a total cost of 2,020 million euros in 2018, 1,256 euros per inhabitant, a figure equivalent to 3.9% of the GDP of the metropolitan region (CE Delft, 2020). In addition, the 119 extra hours behind the wheel in the case of Barcelona (equivalent to 14 working days) translate into an enormous economic loss of 175.5 million euros annually (Tomtom, 2017). According to Holub et al. (2020), the reduction of PM10 concentrations between 2005 and 2014 in Spain avoided more than 5.55 million days of absence due to temporary disability, which would have cost 503 million in productivity losses.
Around 23% of trips in Barcelona are by private vehicle. They enjoy 85% of the lanes. Cars and motorcycles alone account for around 80% of the circulating fleet. Car trips transport an average of 1.21 people; in the metropolitan area, 54% of trips are by a single occupant. Non-work mobility accounts for around 54% of car trips and 37% of motorcycle trips.
Both the expansion of the use of more environmentally sensitive alternatives, such as electric or hybrid vehicles, and possible improvements in the collective transport offer ---any frequent user of the Rodalies network knows about the terrible quality of the service--- will help moderate the severity of the problem. However, in no major city have these changes generally been sufficient to prevent the massive influx of private vehicles into urban centers.
Both the expansion of the use of more environmentally sensitive alternatives and possible improvements in the collective transport offer will help moderate the severity of the problemA recent report by the Ostrom Institute performs a comparative analysis of the various instruments to reduce urban pollution. Quantity restrictions (such as Low Emission Zone) have a moderate effectiveness that declines as the vehicle fleet is renewed. They are also regressive because avoiding or satisfying them is linked to income level.
On the contrary, price restrictions (tolls or fees), applied in cities such as London, Stockholm, Singapore, New York, Milan, Palermo, Oslo or Gothenburg are effective and long-lasting. Instead of prohibiting circulation, they subject it to a pay-per-use system. He who pollutes, pays. In Stockholm, after six months of the fee's operation, NOx emissions were reduced by between 5% and 7.5%, and PM10 decreased by between 15% and 20%. Medical visits for severe asthma episodes in children and young people between five and twenty years old fell by 46% after three years (Simeonova et al, 2018).
The Ostrom Institute report recommends establishing an urban electronic circulation toll with dynamic pricing composed of a congestion charge based on vehicle size and schedules, and an emissions charge based on emission factors and kilometers traveled. Its revenues would allow for resizing the urban public transport service, with a clear progressive effect, and installing air purifiers at critical points. It would improve the quality of life in Barcelona by bringing efficiency to mobility, reducing congestion, and decreasing cardiorespiratory morbidity and mortality, especially among children.