This text is taken from a personal study from 1998 carried out for the Development Economics exam at the Faculty of Statistical and Economic Sciences-Sapienza, Rome. Data provided by the Light Pollution Commission-UAI were used.
Light pollution consists in the breaking of the natural day/night or light/dark balance due to inadequate lighting, in other words the excessive and uncalibrated emission of light rays from poorly designed artificial sources: streetlights, floodlight towers, advertising signs, globes, lanterns... The main effect is the formation of a luminous dome above every human and industrial settlement, with a consequent action that wipes out the view of the sky. Just think that the light produced at night, today, by a small town equals the light spread by a medium-sized nation of the last century! Paradoxically, humans are creating a “daytime night”.
The situation improves slightly when leaving cities, but even in open countryside you can notice a light dome that, mixing with air pollution, erases the view of the sky.
However, the “reflection factor” must also be considered, namely the impact of the reflection of polluting light by clouds, industrial fumes (an industrial district can increase the phenomenon by 60-70%), atmospheric dust, haze and the lithometeors smoke and smog; all this increases the polluting phenomenon exponentially.
Certainly observational astronomy, based on the complete darkness of night, could not have been born under such conditions. Now, with an almost daytime night, huge negative effects arise from a scientific point of view: the major astronomical observatories are located in the few areas that are still dark, belonging to countries not yet well developed economically and energetically, such as Chile, Peru or the Canary Islands. This entails heavy budgets for universities or other research bodies, which must pay for very costly operations, off-site maintenance and long missions for research professors. The effects on humans are cultural: constellations are seen only in schoolbooks.
The National Light Pollution Commission (C.N.I.L.) of the Unione Astrofili Italiani (U. A. I.) stresses how night lighting damages the surrounding ecosystem by modifying, for example, the cycle of chlorophyll photosynthesis, which can be altered by artificial light sources; this change can lead to an alteration of oxygen and carbon dioxide inputs into the troposphere by the flora of our Biosphere, with climatic consequences and, as we will see later, also with an impact on the greenhouse effect.
Well-known are examples of bird migrations misled by city lights and a singular case that happened in the town of Kaktovik in which some bears destroyed several streetlights because they disturbed their sleep. The light produced at night would also slow the brain’s production of melatonin, with negative physical as well as psychological consequences on individuals.
Sensitive to this problem, in the eighties, the International Astronomical Union takes a stand and founds the International Dark-Sky Association (I.D.A.). In 1998 the Unione Astrofili Italiani founded the National Light Pollution Commission. From 2001 to today, regional laws have been approved in 18 regions. As many as three Italian technical standards refer directly or indirectly to light pollution (UNI10819, UNI10439, UNI9316).
On June 10, 2016 the new World Atlas of light pollution was published in Science Advances. The publication involved various research fields ranging from astronomy to demography, up to ecology, to engage politicians on energy-efficiency issues. The atlas was drawn up by an international team, but the greatest contribution was made by the Italians Pierantonio Cinzano, Riccardo Furgoni and Fabio Falchi, president of CieloBuio.
Polluting artificial lights
Artificial light alters the mechanism of chlorophyll photosynthesis, and therefore also the oxygen–carbon dioxide ratio resulting from the natural process; however, even if the Mauna Loa meteorological observatory (Hawaii, U.S.A.) records carbon dioxide variations due in part to absorption by plants, there are still no reliable mathematical models to assess the extent of such alterations.
Instead, we can consider how much carbon dioxide emissions from industrial processes would decrease in the face of a serious policy against this type of pollution.
Making lighting systems non-polluting would mean reducing combustion to produce electrical energy by up to 35%; this would entail a reduction of 85% in carbon and 14% in hydrogen. Bearing in mind the equivalent stoichiometric values (1 kg of carbon equals 3.66 kg of carbon dioxide and 2.667 kg of oxygen; 1 kg of hydrogen equals 8 kg of oxygen), we can obtain that about 1.4 tonnes of carbon dioxide would not be emitted into the atmosphere and about 1.5 tonnes of oxygen would not be burned. Extrapolating these estimates to the entire population of the Earth, there would be a decrease in carbon dioxide emissions equal to 75 million tonnes per year!
Robert M. White (director of the U.S. Weather Bureau) states that about 58% of the cause of the greenhouse effect is due precisely to the use and production of energy. Considering that light pollution accounts for about 35% of electricity production, it follows that this phenomenon has an impact on the greenhouse effect of about 20%.
Technically, light pollution can be detected with the “average emission ratio” (R%) estimated as the ratio between the total flux emitted toward the sky (direct and by reflection on the ground and on other surfaces) and the total flux emitted by the artificial source: it ranges from 20% for small towns to 30% for large cities. There are two methods for measuring R% (devised by Eng. Carlo Rossi, U.A.I.): the “magnitude method” and the “scattered luminous flux method”. With the first, the luminous flux scattered by a city can be calculated indirectly, but estimation errors of 100% may occur depending on how the sampled area is subdivided; with the second, instead, the average emission ratio can also be calculated; the latter is more accurate, with errors of 10%, because it is based on the technical characteristics of the light sources.
Detection techniques
- Measurement of night-sky brightness at various points of the celestial sphere
- Measurement of scattered artificial light using a photometer
- Photographic measurements
- Visual estimates
- Spectral measurements
The light erases the stars
Economic implications
Often, to balance the budget, municipal administrations propose the usual increases in local taxes. The energy/economic savings achieved by removing unnecessary lights would ease citizens’ burden from municipal levies. Significant in this regard is the example of Civitavecchia (Rm) and Frosinone, which approved a specific municipal regulation and replaced part of their lighting stock. Generally, action plans for each municipality should be prepared by qualified Technical Offices for adoption and practical implementation, something not always possible since some municipalities do not have the financial resources available or in any case need technical support, given the specificity and novelty of the topic.
In 1999 I carried out a study on the topic: “Ecological problems and development”, from which a series of economic advantages at national level can be inferred, resulting from a reduction in light pollution. The conclusions of that analysis are:
- savings of 464,645 tonnes of fuel per year.
- energy bill for imported fuels cheaper by 50 million Euros.
- 1,400,000 tonnes of carbon dioxide not released into the atmosphere.
- 1,500,000 tonnes of oxygen not burned.
- savings of 10 million Euros in taxes for electricity-producing companies, thus a cheaper bill for citizens.
- savings of 200/300 million Euros for municipal budgets and for citizens, due to the reduction of light flux directed toward the sky.
- additional savings of a few tens of millions of Euros due to the use of lamps with higher luminous efficiency.
- targeted investments can bring the following positive results: system uniformity.
- optimization and standardization of warehouse stocks with lower maintenance costs and reduction of the costs of building new lighting systems from scratch.
The increase in the world population, from 2.5 billion people on planet Earth in 1950 to 10.8 billion in 2150, according to an average forecast (prof. Golini, “Population Division of the Department of Economic Affair at the UN Secretariat”, 1998), and the technological growth in the underdeveloped areas of the planet is radically changing society’s scenarios and irreversibly damaging the balances of the biosphere.
What will happen to the Planet’s development when the underdeveloped population grows and feels our same need for energy? There is no answer, yet more or less realistic scenarios can be assessed. To avoid possible ecological or energy crises, suitable policies must therefore be applied in each single nation; small individual measures to save energy are also important and, if considered globally, can bring beneficial effects on the entire biosphere. Properly aiming a light bulb may seem little, like the damage caused to the environment by a single individual, but multiplying the little by five billion becomes an ecological bomb. Therefore, not only the scientific community, but the whole society is called to rethink its relationship with the environment according to a new mindset that promotes critical and active behaviors toward its own habitat. A greater sensitivity is therefore required toward the complex relations between the biosphere and human activities, able to distinguish the resources to pass on from those to consume, and able to enhance the environmental resources inherited to create new dynamics of production, in the perspective of sustainable development.
How to join the fight against light pollution.
I believe we must act on two fronts: the first operational and the second cultural.
On the operational front I suggest getting in touch with Amateur Astronomer Associations to learn about the regulations in force and to follow their procedures to report abuses.
On the cultural front it must be made clear that it is a problem both medical and energy-related. Moreover, we must pass on a culture of love for the sky and debunk some common misconceptions such as:
- The problem of light pollution concerns only astronomers
- It’s enough to leave the cities to see the sky
- Low-pressure sodium lights are inadequate
- Overlighting prevents crime
- Fighting light pollution does not mean living in the dark
- To landscape photographers I suggest not using polluting light as an artistic element in the image composition, so as not to convey the idea: “more light” equals “more beautiful”.
Globe Streetlamp
polluting
Cut Off Streetlight
non-polluting
The light of Rome 80 km away wipes out the low stars on the horizon
