Environmental pollution is directly related to the evolution of technology and science, the progress of which, in addition to significant benefits to mankind, also has adverse effects on the environment and hence on human health, the so-called “price of evolution” .
Today, air transport occupies a significant part of the passenger and freight transport activity. It accounts for over 3.3 billion passengers per year and 60 million jobs, accounting for 3.5% of global GDP. At the same time, however, the aviation industry produces about 2% of the world’s man-made CO2 emissions, which are the cause of the ozone depletion and global warming.
The United Nations Intergovernmental Panel on Climate Change (IPCC) said in a report that carbon dioxide emissions rose 3% per annum from 1990 to 2015, contributing 3.5% to global warming. Other estimates raise this figure to 6%, while they even expect an increase of 300% by 2018. The scenarios show that the share of the whole aviation – international, national, military and other – as a source of CO2 emissions may increase to over 15% of total CO2 emissions in 2050.
However, CO2 is not the only greenhouse gas emitted by aircraft and is expected to increase in the future. Exhaust from aircraft engines consists of about 0.03% nitrogen oxides (NOx), volatile organic compounds (VOC), unburned hydrocarbons, carbon monoxide (CO), other trace elements such as
sulfur dioxide (SO2) hydroxide, nitrite and nitric acids and finally small amounts of soot particles (PM).
As far as the ozone is concerned, airplanes create it as a result of the reaction of nitrogen oxide with various volatile organic compounds, a reaction which is catalysed by sunlight. Essentially, ozone can be produced from dry O2 driven to an area where high-voltage electrical discharges occur. The ozone hole raises today the interest of millions of researchers trying to find a solution to this ominous problem.
Among other things, the short-term impact of aircraft is strongly enhanced by cyclical clouds. In particular, SO2 forms sulphate particles and soot particles from the exhaust gases of the aircraft. These aerosols act as seeds which water vapor condenses or freezes by turning them into cloud particles (circular clouds). The exhaust of the aircraft produces condensation paths about 5 miles above the Earth’s surface and forms nicks. All these reflect the sunlight and absorb heat instead of letting it go.
It is worth noting here that emissions of pollutants depend on different phases of the flight, such as landing, sailing and take-off, since they require different engine power settings for the airplane. Both the amount of fuel consumed per second and the amount of pollutants per fuel unit may vary for each power setting. In particular, an aircraft uses a higher power setting during take – off typically about 70% of its total power, so it uses more fuel and will emit more pollutants for a few seconds, while during the course the engines will run at about 15-30% of total power this time but for several minutes. Finally, during the landing, aircraft engines will operate at less than 30%, so emissions per second will be much lower than any other phase. Also, the higher the airplane flies and the heavier it is, the harder it can be to break the CO2 into the atmosphere.
Aircraft manufacturers and airlines are working on ways to reduce pollutant emissions by increasing fuel efficiency – by making lighter and more aerodynamic airplanes, trailing fins on the ground and improving engine capacity. Designers even look at the case of aircraft using biofuels while it has been proposed to build a biological jet from next year. However, industry experts believe that these changes could improve efficiency by 1% or 2% per annum at most, while passenger miles will increase from 5% to 6% per year, confirming the sustainability gap. It is obvious, therefore, that scientists, activists and parliaments should work together to find a solution to this enormous environmental evil.
The environment is also directly connected with human health, which is seriously hindered by the lack of scientific initiative! Changing legislation to eradicate morbidity and mortality is imperative. If we wanted to pinpoint the issue of human health, we could say that the suspended particles of the airgass smoke can cause immediate and chronic effects on the human organism. Due to their diameter, they can be deposited in the tracheobronchial area (TB) of the respiratory system, even reaching the alveoli. They have the property of weakening the natural functions of the human, resulting in disfunctions of the nervous system, the right ventricle of the heart, in the bloodstream and can cause swelling and inflammation of the lungs. The most important impacts of air pollution are on the health of people in specific vulnerable groups. More particularly, we can mention the following examples:
a) Carbon monoxide reacts with blood hemoglobin and at high concentrations can lead to visual abnormalities, poor assessment of space and time and possibly anesthesia. Also, UV-C radiation is the cause of the cataract, as it is strong enough to pass through the retina of the eye.
(b) Sulfur dioxide affects the respiratory system, particularly when combined with high concentrations of suspended particles
c) It is the primary cause of melanoma, a form of lethal skin cancer. In Australia, where UV radiation is 15% more than Europe, it was estimated that in 2011, melanoma cases were increased by 23% for women and 28% for males compared to 2002.
d) Ozone is extremely toxic and exposure of the individual to high concentrations may cause dizziness, etc.
e) Last, and potentially, the main effect of UV-C radiation on living organisms is the mutation of their DNA. Indeed, it is so powerful that scientists use it in laboratories and under appropriate conditions to achieve gene mutations. In particular, UV-C alters the DNA to such an extent that it gradually loses its ability to divide and multiply.
It is obvious that the treatment of illnesses that are caused by aircraft costs trillions globally.
A prudent solution for removing harmful pollutants from the atmosphere is tree planting in large areas around airports. In the global fight for greenhouse gas mitigation, forest production has proven to be the most effective medium-term strategy. This conclusion has been reached by the scientific world, having identified the crucial role the forest plays in limiting carbon dioxide. Plants use light for photosynthesis, converting carbon dioxide into carbohydrate and releasing oxygen at the same time. The scientific team has now discovered that when carbon dioxide is bound by trees, it is stored in its trunk and in the soil under their roots while remaining on the leaves for a longer period of time, acting as a fertilizer and accelerating the growth of the plant. So we see the double profit we have in a tree planting initiative: the exhaust gases for which there is no way to be limited, are ultimately absorbed by the foliage of trees by benefiting the tree itself.
An airline crew who has realized how many pollutants it produces in each flight has already taken action, giving the example to other airlines and sensitizing its passengers to exert pressure.
Εnvironmental Εngineer at Technical University of Crete
Arid Zone AfforestationNPO (AZA) is a non-profit organization that acts to combat desertification on a local and global level, in arid, semi-arid, and deserted regions, where rainfall is limited or non-existent, by the use of innovative, environmentally friendly planting technologies, such as the Safe TreeΤΜ planting system.