Major new study on light pollution in Malta

A team of scientists has carried out a landmark study that quantifies the problem of light pollution in Malta. The peer-reviewed work has been accepted for publication in the prestigious Journal of Environmental Management.

It carries the first ever map of the night sky brightness for the Maltese archipelago, which is also one of the highest resolution maps ever produced in a study of this kind.

Led by astrophysicist Dr Joseph Caruana from the Department of Physics and the Institute of Space Sciences and Astronomy of the University of Malta, the publication details work that was carried out by the group over a number of years, looking at how the night sky brightness varies both geographically and over time. Geographical data was collected over two years since 2017, whereas temporal data was obtained on a daily basis since 2014. The study also looks at the effects of light pollution on ecology and human health. It identifies the main sources of light pollution in Malta and proposes a number of suggestions to address present issues.

Light pollution is increasingly becoming a major focus of studies worldwide. Besides signifying energy wastage and the erosion of the cultural appreciation of the night sky, it carries several other repercussions. A number of studies have linked light pollution to problems of psychological wellbeing as well as various types of cancer, specifically via the suppression of the hormone melatonin. It is also becoming ever clearer that light pollution has a serious impact upon ecology, with various species being affected.

The study finds that the vast majority of the area of the Maltese Islands is heavily light polluted, with the Milky Way being visible for just 12.8% of their area. Moreover, the measurements show that the night sky brightness is increasing over time, effectively meaning that the problem of light pollution is getting worse.

The study also looks at the night sky brightness as perceived by local Shearwater, a cliff-nesting bird species that is sensitive to light pollution. The prevailing level of night sky brightness over the archipelago is also impinging upon Dark Sky Heritage Areas in coastal zones in Gozo; these are designated sites that allow the appreciation of the night sky and offer nocturnal creatures a respite from artificial lighting. In Malta, the worst affected town is Birkirkara; in Gozo, Victoria and Għajnsielem are the two brightest zones. The least affected site in Malta is Rdum tal-Vigarju (cliffs off Baħrija, limits of Rabat), whereas in Gozo, the darkest region is Ta’ Ħarrux (off Dwejra).

Among its conclusions, the study notes that all identified main sources of light pollution can be effectively mitigated via proper regulation of outdoor lighting and it makes a number of recommendations in this regard, including the use of properly-designed lighting fixtures that direct their light downward and the adoption of luminaires that emit at a warmer colour, which results in less scattering of light.

In technical terms, these desirable fixtures are said to have a correlated colour temperature less than 3000K. On the other hand, existing road lighting in Gozo utilises lighting fixtures that emit light with a CCT larger than 3000K, with the same type of luminaires now being introduced in Malta. Furthermore, the work proposes the establishment of a perimeter and buffer zone that would help conserve Dark Sky Heritage Areas. A new DSHA is also proposed for Malta, namely at Rdum Majjiesa (near the Majjistral Nature & History Park) and the area stretching between Rdum tal-Vigarju and Miġra l-Ferħa.

Since the study is very well placed to raise further awareness about the problem of light pollution and to help shape policy, a seminar for interested organisations and government agencies and authorities will be held in the near future, with a view to presenting the results in detail and addressing present concerns.

Further information, as well as a link to the research paper, may be accessed online.