- Maritime transport is an essential asset for the European economy.
- Cruise travel has become an important source of income in many coastal cities.
- The main ship emissions are SO2, NOx, suspended particles and noise.
- Real-time monitoring of air quality using low-cost sensors presents itself as one of the most efficient measures.
Maritime and river ports are essential infrastructures for the economy of the countries. They create employment opportunities and boost the economy through the transport of goods, logistics operations, fishing and, in later years, cruise travel.
However, all that frantic activity has a hidden side: the air pollution caused by ships. Therefore, the measurement of air quality at ports is a point of interest. And this is not only due to issues of environmental quality but also because of the way the public image is improved by those port authorities who opt for this solution.
Port Activity: Brief Contextualisation of the Industry
According to Martin Dorsman, ECSA Secretary General, maritime transport is ‘one of the most valuable assets in Europe‘. Thus, data from 2018 indicate that it directly contributed 54,000 million Euros to the European GDP. Likewise, it provided jobs for around 2 million people through direct or indirect employment.
However, since a few years ago, one of the activities with the highest growth is related to holiday cruises, and not just in the number of operations. Both the routes available and the passenger numbers have increased significantly (1). So much so that Spain exceeded 10,000,000 passengers in 2018, a figure which represented an inter-annual increase of 9.66 %.
The graph below shows the fifteen Spanish ports with the highest number of cruise passengers during 2017 and 2018 (2):
What does this vibrant cruise traffic translate into? Into a source of income which, for example, in Catalonia, exceeded 1,000 million Euros (data from 2016). This figure represents a turnover of €518 per passenger, according to the newspaper La Vanguardia in January 2018.
Air quality at ports, what impact do ships have?
However, one of the handicaps for maritime traffic is the reduction in air quality, caused by the type of fuel used by ships. According to a Transport & Environment Report, in 2017, just in Europe, 203 cruises «released around 62 kt of SOx, 155 kt of NOx, 10 kt of PM and more than 10 Mt of CO2».
Main polluting emissions released by ships
The main emissions released by ships are:
- Sulphur dioxide (SO2), which originates from burning fossil fuels. Breathed in high concentrations, can cause problems in the respiratory tract. Mixed with water, can generate acid rain.
- Nitrous oxides (NOx), which are also generated from fossil fuels. Apart from their effect on health (airways irritation, lung failure, etc.), it has a strong impact on water eutrophication.
- Suspended particles (PM1, PM2.5 and PM10), are made of soot, ash and other particulate materials. They are hazardous because of their tiny size, since they can reach the deepest areas of the respiratory system and, from there, the bloodstream.
- Noise, both from the ships and from the passengers or the port activity (vehicle traffic, loading and unloading of cargo, etc.).
This decline in air quality is not limited to port areas. Thus, coastal cities like Marseille observe an increase in cancer cases which suggests a possible correlation and, in other cities like Gothenburg, the NO2 levels from the ships exceed those caused by traffic areas near the port (3).
With regards to suspended particles, for example, considered by the WHO a very harmful pollutant, it is worth mentioning the research by Ryan D. Kennedy, from Johns Hopkins University (4). In the framework of this study, measures were taken on various cruise liner decks. The results confirmed a high quantity of suspended particles generated by these ships. In some aft areas exposed directly to the emissions from the funnels, the concentrations were comparable to those found in cities such as Beijing, this being a significant problem even at sea.
Solutions to reconcile economic growth and well-being
Decarbonisation and improvement in air quality at ports is an urgent task. In this regard, one of the elements emerging more strongly is Green Ports.
Their objective is to minimise the environmental impact on the atmosphere, marine resources, biodiversity, and inhabited areas nearby.
An essential measure within the framework of these sustainable ports is real-time, continuous atmospheric monitoring. The deployment of air-quality meters enables port authorities to:
- Detect the presence of hot spots.
- Establish alerts for high levels of contamination.
- Adopt measures based on actual contamination information.
A practical example of the benefits brought about by this solution is the project that Kunak finished in cooperation with Labaqua for the Port Authorities in the Balearic Islands. This initiative has led to the installation of 25 devices that monitor contamination levels and noise in different maritime ports on the islands.
Nevertheless, other methods have also been adopted with the aim of reducing the problem.
One of the highest-impact decisions has been, without a doubt, the enforcement of a new standard related to sulphur oxide emissions. Decreed by the International Maritime Organisation and in force from 01/01/2020, it establishes a new limit on the contents of sulphur in fuel used in boats, from 3.5 % mass/current mass to 0.5 %.
However, the answer for many shipping companies has been the installation of scrubbers or gas scrubbers. This alternative allows the same type of fuel to be used but reduces sulphur emissions. The problem is that, in many cases, surpluses are poured into the sea, which may put marine biodiversity at risk.
Furthermore, another measure being studied by ports such as Barcelona is the electrification of the docks. However, this is a long-term solution that, in the case of the Catalonian capital, will not begin to materialize until 2021.
Port activity is fundamental for the economy of coastal nations. Yet, many operations they perform compromise air quality. The emissions from boats are one of the main sources of conflict, but not the only one. What is the best way to identify the problem? Deploying low-cost air-quality sensors that make continuous, real-time monitoring possible.
- (1) Ruiz-Guerra, I., Molina-Moreno, V., Cortés-García, F., & Núñez-Cacho, P. (2019). Prediction of the impact on air quality of the cities receiving cruise tourism: the case of the Port of Barcelona. Heliyon, 5(3), e01280. https://doi.org/10.1016/j.heliyon.2019.e01280
- (2) Spain, a country for cruise passengers: 10.1 million passengers in 2018 (08/04/2019). State Ports. Ministry of Public Works. Consulted on 18/02/2020 at http://www.puertos.es/Documents/Notas%20de%20Prensa/NPSeatradeMiami.pdf
- (3) Tang, L., Ramacher, M., Moldanová, J., Matthias, V., Karl, M., & Johansson,
L. et al. (2020). The impact of ship emissions on air quality and human health in the Gothenburg area – Part I: 2012 emissions. Atmos. Chem. Phys. Discuss., 2020, 1–36. https://doi.org/10.5194/acp-2020-94
- (4) Kennedy, RD. An investigation of air pollution on the decks of 4 cruise ships.
A report for Stand.earth, January 24, 2019. Consulted on 19/02/2020 at https://www.stand.earth/sites/default/files/2019-an-investigation-of-air-pollution-on-the-decks-of-4-cruise-ship.pdf.