Air pollution occurring on the Portuguese coast caused by passing maritime traffic represents around 20 per cent of pollution caused by nitrogen oxides (NOx), one of the most harmful pollutants to human health and the environment.
This figure comes from a study done by the University of Aveiro (UA), which in order to help reduce this contribution, points out a list of measures that need to be put into practice.
“Maritime emissions, which mainly comprise NOx and sulfur dioxide (SO2) pollutants, have a large impact dye to international routes, this impact reaches the coastal zone, with contributions ranging from 10 to 20 per cent for NOx, and above 20 percent for SO2,” says Alexandra Monteiro, a researcher with the Centre for Environment and Sea Studies, one of the AU's research units.
The study's coordinator said it presents a “worrying scenario” that must be tackled urgently: “it is very important to put in place the measures proposed by the research team, some promoted by Europeans regulations themselves, especially in view of the continuous and expected increase in maritime traffic”.
Researchers estimate that currently approximately 90 per cent (75 per cent in Europe exclusively, and growing) of all trade in goods around the world is carried out via the sea, making this mode of transport worrying in terms of environmental impact, mainly due to its high dependence on the use of fossil fuels, with have a strong association with atmospheric emissions and potential impact on air quality.
Coordinated by Alexandra Monteiro, the recently completed AIRSHIP project aimed to assess the impact maritime emissions on air quality in Portugal and, in greater detail, at the local level. As a case study Porto Leixões and the surrounding urban area was used.
Under this project, the AU researchers, in collaboration with the Finnish Meteorological Institute, made estimations regarding the atmospheric emissions associated with maritime transport off the coast of Portugal, and evaluated the contribution of these emissions to air quality using a numerical modelling system.
The results showed that these emissions have a massive impact on air quality along sea routes, and this problem radiates to nearby to coastal areas on land. In these locations there are dangerously high contributions of the two of the most critical pollutants, exceeding the recommended limit values.
Among the dozens of measures identified to reduce these pollutant emissions, the researchers underline the importance of reducing ship speeds while in operation close to the shore, and using alternative fuels to reduce the use of more crude traditional transport fuels. Moreover, changes to the ship's engines are recommended to make their emissions cleaner, and the implementation of an exhaust gas cleaning system on ships are among the many measures proposed.
"We hope that these results are useful in the management and promotion of political action in the field of maritime transport and its environmental impacts, thus placing science and research at the true service of society," says Dr. Monteiro.