Cargo vessel atmosphere pollution
While everyone is focused on CO2 (and we do need to pay attention to that), cargo shipping appears to be the more eco-friendly: only 10 grammes of CO2 to transport one tonne of marchandise on one kilomètre (18g by train, 47g by truck et 560g by plane).
But cargo vessels are using diesel engines that burn high sulfur content fuel oil. It generate more than 3 000 à 3 500 ppm Sulfur dioxide. While the european norme indicates that the car emission can't exceed 15ppm. Therefore, one cargo ship emit as much Sulfur Dioxide as 50 million car...And there are more than 80 000 cargo ships (over 120m long) sailing accross the earth.
The 16 biggest cargo emit as much Sulfur Dioxide as all the car in the world!!! Inhaling sulfur dioxide is associated with increased respiratory symptoms and disease, difficulty in breathing, and premature death.
New diesel engines burn less fuel (still between 150 and 300 tonnes a day), and emergency measures are taken, such as chimney evacuation filters or increasing controls and penalties. Despite all the effort to reduce the atmospheric effect of maritime fret over several years, there is still a lot to do about every other pollution generated by this traffic (Sound pollution, Wildlife collision, Ballast water, etc.).
This map represent the average density of cargo around the world.
For more information:
A good wikipedia page: here
NOAA article: here
And one in french: here