Emissions into the Air







Air pollution has been an important environmental issue since the 1970s. However, air pollution regulations for seagoing ships have been relatively recent. Since 1997, the IMO has been actively working at regulating the emission of polluting substances by ships (MARPOL Annex VI).  


Participants will:  

  • Explore how emissions into the air have contributed air qualify, acidification and climate change 
  • Learn ways to reduce the amount of air emissions released 

Climate Change: Any change in climate over time, whether due to natural variability or as a result of human activity.  


Important air pollutants from ship engines are carbon dioxide (CO2), sulfur oxides (SOx), nitrogen oxides (NOx), and Particulate matter (PM). These air emissions from ships are influencing air quality for human health, acidification, and climate change.  

Dive Deeper

Air Quality

Air pollution that most impacts human health are smog and particulate matter (PM). Nitrogen oxides (NOx), and sulfur oxides (SOx) contribute to the various types of smog. Ozone (O3) is a main component of smog and is dangerous to human health when found at ground level. It irritates the respiratory systems and eyes. Exposure to high levels of ozone results in chest tightness, coughing and wheezing.  

Particulate Matter (PM) represents very small particles. When inhaled by humans, these particles can be problematic. Particles larger than 10 micrometers are removed by the body through coughing. Smaller particles may remain undetected in our airways. These particles, less than 2.5 micrometers, are the most harmful to humans. Effects include asthma, hearth attacks, heart and lung disease.  

Effects of air pollution on humans. (Source: European Environment Energy)

Diagram of ocean acidification. (Source: Dolphinaris)


Acidification is caused by nitrogen oxides (NOx), sulfur dioxide (SO2) and ammonia (NH3). In the air these compounds react with water and strong acids are formed. These acids increase the acidity in the environment and cause a variety of damage, including: 

  • Essential nutrients leach out and disappear to the ground water, resulting in decreased soil fertility 
  • Soil releases toxic heavy metals 
  • An overload of the nutrient nitrate from acidification may cause algal blooms and oxygen shortage in surface waters 

Climate Change

Climate change is one of the most serious environmental problems facing the world today. It is a pressing issue on political agendas, and receives a lot of attention in the media. The International Maritime Organization (IMO) has developed a package of measures for reducing shipping’s CO2 emissions. 

Scientists agree that our world climate is changing: global air and ocean temperatures are rising, snow and ice are melting, and sea levels are rising. In the history of the Earth the climate has been changing constantly, due to variations in natural processes. However, according to the Intergovernmental Panel on Climate Change (IPCC), during the last century the changes in the climate are unequivocally caused by human activities. 

While there is scientific consensus about the fact that the climate is changing and that human activities are playing a role, the impacts of climate change, and the future developments, are much more uncertain. Nonetheless, there are many examples of the natural system reacting to climate change, includinghigher frequency of extreme weather conditions; change in geographical distribution of species and possible extinction of some of them, changing geographical distribution of some infectious diseasesflooding of land areas, ocean acidification, and warming of the ocean causing death of phytoplankton and corals 

What can you do?

The maritime industry is working hard on establishing regulations and developing innovations to cut emissions of the shipping industry. While some solutions require business choices and large investments, everyone can play a role in cutting emissions. We can all use energy wisely, as an individual, or in our professional capacity as a seafarers or port employee.   


Many measures to reduce greenhouse ship emissions of ships are already available and include technical measures related to hull and ship design and the use of alternative fuels and power sources. As a seafarer you can also contribute by changing the operation and maintenance of a ship. For example, increasing energy efficiency by using weather planning, voyage planning like just-in-time-management, proper maintenance and slow steaming save money and cut emissions.  

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