Air pollution: How it impacts, and is impacted by, city life

Flowing on from last week’s post on the production of nature and the ecosystem services Parc de Collserola provides, this week looks at the issue of air pollution in the city of Barcelona.  

Due to Barcelona’s urban density, lack of green space, warm climate and private vehicle use, it is one of the most polluted cities in Spain. The two main pollutants Barcelona faces are nitrogen oxide (NO2) and particulate matter (PM10), which come predominantly from traffic and to a lesser extent from construction work and the industrial sector. Barcelona’s air pollution problem is a product of its rapid urban growth and development, with CO2 levels having more than doubled since the 1990s. 

Environmental exposure maps of Barcelona at census-tract level (n=1,061): (A) air pollution, P.M2.5 annual mean; (B) daytime road traffic noise, LAqe,16hr (0700-2300 hours); (C) heat, daily mean temperature for 1 July 2011; (D) green spaces, green space surface in percent (GS%) of green spaces ≥ 0.5 ha.
Source: NCBI.

Both ambient (outdoor) and household (indoor) air pollution cause negative health impacts and can lead to cardiovascular or respiratory disease; a 2017 study found exposure levels in Barcelona lead to almost 3,000 preventable deaths per year. Air pollution and its health consequences are not felt equally across the city and tend to impact the those living in the most deprived areas the most; with those that gain the most from polluting activities often being impacted the least. In Barcelona, this is seen as areas with higher levels of ethnic groups face higher exposer to NO2 than the city’s general population. 

Despite this unequal distribution of air pollution across neighbourhoods, official monitoring systems in cities tend to be based on sparse networks of monitors, producing ‘baseline’ data that summarises the state of air quality in neighbourhoods or regions. This has been criticized by urban political ecologists, as these systems fail to capture localised human exposures to pollution. In Barcelona, 11 stations, monitoring over 10 pollutants, make up the Atmospheric Pollution Monitoring and Forecasting Network. The stations are in locations that represent different street categories (urban-area, suburban and traffic) in order to obtain data that can be extrapolated to other areas with similar urban conditions across the city.  

Air pollution monitoring station, Barcelona. Source: Ajuntament de Barcelona, Air Quality.

However, in Barcelona, CITISENSE is working to provide more thorough monitoring of the city’s air. The project is still in its planning stages, but will include both static sensors placed on balconies across the city, and portable sensors to be worn by volunteers for a period of one week to one month. Projects such as these that will provide a more accurate understanding of air pollution across the Barcelona may enable the city to make changes in the most polluted areas, readjusting the distribution between the previously mentioned ‘winners’ and ‘losers’ of air pollution.

Urban residents are often responsible for creating the air that they breath, and the city of Barcelona is no exception to this. Urban and regional traffic are the biggest contributors to air pollution in the city, accounting for 48.2% of NOx and 61.6% of PM10 emissions. Over the past few years, the city council has been very active in introducing policies to reduce private vehicle use and promote public transport, cycling and walking in an effort to reduce air pollution. Most recently, as of 1 January 2020, the Barcelona Ring Roads LEZ has been introduced; an area of over 95kmwhere the most polluting vehicles are restricted, with the aim of reducing environmental and health problems associated with air pollution. The city’s innovative urban planning superblock policy is also intended to have a significant impact on air and noise pollution, with ambient levels of NO2 predicted to reduce by a 25% in superblock neighbourhoods. The policy creates ‘superblocks’ of nine city blocks where traffic is restricted to roads around the outside and streets are turned over to pedestrians and cyclists.  

Superblocks model explained. Source: Ajuntament de Barcelona, Urban Mobility Plan of Barcelona.

Air pollution in Barcelona is an element of city life that greatly impacts, and is impacted by, the behaviours and activities that occur within the city. Its effects are felt unevenly across the city, with winners and losers not reflecting responsibilities. Whilst this post has discussed improvements in monitoring systems and urban policies that are movements in the right direction, more action needs to be taken to make Barcelona a more equitable city in terms of air quality.  

3 thoughts on “Air pollution: How it impacts, and is impacted by, city life

  1. Hi Alex, thank you for this very clear presentation of the air quality issue in Barcelona. As I come from Southern Europe myself, I can see that many Mediteranean cities are confronted with the issue of trafic and air pollution despite reaching an almost optimal density in city-centers. Therefore, I am left wondering how this issue can be linked with political culture and historical choices. How is the city governed? What is the Mayor’s role in today’s initiatives such as the Superblocks? Who decides in Barcelona and under what principles? From my incomplete experience of cities like Barcelona, Marseille or Athens, they seem to have failed to deter citizens from individual car use and to encourage a polycentric development, providing suburbs with sufficient amenities to limit their dependance to the center. I think a crucial part of Urban Political Ecology is to explore the interconnectivity between political and natural flows – i.e. connections, influences, origins, … – structuring the city. I would be very interested in knowing your personal take on the issue, and the political analysis that you could draw from the very informative description you made here.


  2. This post was a really great read. I’m particularly interested in Barcelona’s innovative urban planning strategies, and as you mention, the superblock concept looks set to help reduce air pollution levels overall. It’s great to see a municipality putting so much emphasis on walking and cycling, but I wonder if directing most vehicle traffic to roads on the perimeter of each superblock may result in a new concentration of pollutants on those particular roads. I wonder if increased pollution along certain streets might bring on an unwanted wave of criticism and NIMBYism for the local authorities as they implement the superblock strategy.


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