Low Emission Zones, a Tool Introduced by New Climate Change Legislation

June 30, 2021


  • The new law on climate change and energy transition that has entered into force will force hundreds of municipalities in Spain to mark out low-emission zones.
  • Environmental monitoring systems with air quality sensors such as Kunak AIR Pro are useful tools for analysing how these areas develop.
  • Implementation experiences in numerous European cities have been positive, with a reduction in both the number of vehicles that pass through urban centres every day and on main pollutant levels.


At last, in May 2021, Spain finally approved the law on climate change and energy transition.

Although described by some environmental groups as «late and insufficient», this new legislation should serve to lay the foundations for a more sustainable future with lower emissions. Instruments for achieving this, such as low-emission zones, are a solution that benefits air quality.


Basic notes for a law that makes promises and commitments

One of the main goals of this new regulatory framework is to advance towards a decarbonised economy. When all is said and done, reducing atmospheric emissions is a sine qua non for maintaining hope on the 2015 Paris Agreement commitments and action programmes such as Towards Zero Pollution for Air, Water and Soil.


How to achieve this goal?

Committing to activities that contribute towards minimising emissions is undoubtedly one of the best ways.  Thus, this law outlines a series of strategies aimed at:

  • Promoting renewable energies.
  • Refurbishing buildings to improve energy efficiency.
  • Reducing emissions in key sectors such as seaports, is one of the areas in which Kunak has become a benchmark company, thanks to its air quality monitoring systems.
  • Making a decisive commitment to sustainable mobility.

However, instruments like low-emission zones certainly stand out, mainly because of the change they will bring to the urban fabric.


Low emission zones, fewer polluting vehicles, higher air quality

From 2023, many cities in Spain will have to display a sign like the one below.


Low emission zones signal


Recently approved by the Directorate-General for Traffic, this new indication will inform drivers that they are entering a low-emission zone.

Low emission zones (LEZ) establish specific emissions standards and make access to the most polluting vehicles more difficult. To the origin of this measure goes back to Stockholm in 1996: the Swedish capital was the first city to implement these zones. However, this solution has spread to other European cities, with London as one of the leading causes of this implementation.


Why are low-emission zones necessary?

Emissions caused by traffic are, to this day, one of the main sources of pollution in urban areas, seriously compromising air quality. Also, it should not be forgotten that this factor is behind thousands of premature deaths and health problems.

However, motor vehicles also contribute to global warming through CO2 emissions. In fact, according to data from the International Energy Agency and the International Council on Clean Transportation, road traffic accounts for almost 75% of the total emissions caused by transport.

Source: Our World in Data, October 2020


It is well-known that Carbon dioxide (CO2) is one of the main greenhouse gases. The increase in its concentration, mainly due to burned fossil fuels, explains to a large extent the increase in temperature on the earth’s surface. Limiting this temperature increase is one of the main commitments agreed of the aforementioned Paris Agreement, which Spain ratified in January 2017 and is, therefore, legally binding.


A closer look at the model to be implemented in Spain

In essence, this climate change legislation is a declaration of intent that seeks to establish minimums.  Thus, its measures will require that detailed regulatory guidelines are set within the framework of each autonomous community’s authority.

In this regard, and although several Spanish cities have already implemented LEZs on their own (Barcelona, Valladolid, etc.), the new law on climate change establishes that:

must mark out low emission zones by 2023 through Sustainable Urban Mobility Plans (SUMPs). These documents must also include other measures. For example, promoting electric mobility or establishing measures to improve air quality in the surroundings of educational and health centres or other particularly sensitive areas.

As a preliminary step to the design of LEZs, it is also recommendable to carry out a study to identify the city’s hot spots. In this way, it is easier to subsequently delimit the area of influence subject to restriction. The best way to undertake this analysis is to use appropriate tools to help define the hotspots and to quantify the levels of air pollution before and after the implementation of the actions. This pre-examination should also take into consideration how to prevent or limit traffic routing to other areas and thus transfer the associated pollution problems.


How many municipalities in Spain have more than 50,000 inhabitants?

Well, as of 01/01/2020, more than 140, mostly located around Madrid and the Mediterranean coasts.


Aid for the creation of low-emission zones

One aspect to be taken into consideration when creating LEZs is the economic aid to be distributed by the Government. These subsidies, included in the Recovery, Transformation and Resilience Plan will be transferred to the Autonomous Communities, which will be responsible for passing them on to those municipalities that require them.

Specifically, two calls for participation are foreseen (2021 and 2022), each involving 750 million euros.

The goals they pursue:

  • Accelerate the implementation of low-emission zones.
  • Prioritise collective public transportation and active mobility as an alternative to private cars.
  • Encourage the transformation of transport towards zero emissions.
  • Promote transport service digitalisation.


What is the role of an environmental monitoring system?

On our blog we have already argued that our solution for monitoring air quality does not replace official stations, but complements and reinforces them, extending their coverage.

Low emission zones are a clear example of the benefits of installing air quality sensors like our Kunak AIR Pro. Some of the benefits include:

  • Assessing effectiveness by obtaining real-time data on pollution reduction on LEZs and on the rest of the city.
  • Supporting the design of LEZs by detecting hot spots.
  • Carrying out development assessments following the implementation of low-emission zones.
  • Predicting air quality thanks to technologies like SUEZ España’s Dinapsis platform.
  • Alerts and technical support to set out pollution protocols.




Learning from other cities

To what extent do low-emission zones improve air quality? The activities carried out in Spain are not yet sufficiently far-reaching enough to draw clear conclusions.

However, initiatives such as Madrid Central, which was definitively annulled by the High Court of Justice of Madrid, made it possible to significantly decrease NO2 concentration (1) during the time they remained active.

Therefore, we are going to show you what is being done in other European cities.


Londres: from low emission to ultra-low emission zones


The example of the British capital is possibly one of the most significant in Europe.

The implementation of these areas, undertaken in several phases, started in 2008 with the aim of addressing and reducing the enormous impact caused by the daily traffic inundating its streets, which placed the city among the most polluted European cities. Compared to previous programmes, the degree of compliance by users was over 95% from the early stages (2).

London currently establishes two types of areas with specific air quality standards:

  • Low Emission Zones (LEZ) are in force 24 hours a day, 7 days a week (with the exception of 25 December). Vehicles driving through them while failing to meet emissions standards will be hit with a daily charge of between £100 and £300.
  • Ultra Low Emission Zones (ULEZ)  are in effect 24 hours a day, 7 days a week (except 25 December), and vehicles that do not meet the standards will be hit with a charge of £12.50 per day for cars, motorcycles or vans and £100 for heavy goods vehicles.

By implementing these measures, especially after launching the ULEZs (2019), has made it possible to cut NO2 pollution levels by more than 35%. Due to their success, ULEZs will be extended from October 2021.


París: results of the Crit’Air system

Paris’ low emission zones came into force in 2015, initially limiting access to heavy goods vehicles registered in or after October 2001.

However, in 2016, France introduced the Crit’Air national air quality certificate, which applies to all vehicles. It defines 5 categories according to the vehicle, fuel and emission type, identifying each means of transport with a sticker which must be visible. This system currently regulates access to different areas of Paris. Various calendar goals have been set during its operation, which will end in 2030. From that year onwards, only electric and hydrogen-powered vehicles will be able to drive in the city and metropolitan areas.

As a result of these measures, Parístraffic has reduced by 31%. In terms of NOx levels, with the implementation of the most restrictive scenarios, it is estimated that in 2024 pollutant emissions could be between 76% and 87% lower than 2016 levels.



Low-emission zones are useful tools to reduce pollution levels in cities. When designed correctly, they work and in those cities that have been using them for some time, results are positive.

However, their implementation requires support elements such as air quality monitors. Checking the evolution of the LEZs requires rigorous, high-quality data to be made available, as those offered by Kunak solutions.


Sources consulted

  • (1) Salas, R., Perez-Villadoniga, M., Prieto-Rodriguez, J., & Russo, A. (2021). Were traffic restrictions in Madrid effective at reducing NO2 levels?. Transportation Research Part D: Transport And Environment, 91, 102689. https://doi.org/10.1016/j.trd.2020.102689
  • (2) Holman, C., Harrison, R., & Querol, X. (2015). Review of the efficacy of low emission zones to improve urban air quality in European cities. Atmospheric Environment, 111, 161-169. https://doi.org/10.1016/j.atmosenv.2015.04.009