*3.3. Measurements of Light Emitted by Luminaires and Electronic Equipment Used by Adolescents*

There is a growing number of articles on the subject of light emitted by luminaires and equipment. In an article published in 2013, Hassoy et al. [53] noted that mobile phones are widely used by children and adolescents. The authors provide data from several countries including 76% phone use in Hungary, 79% in Sweden, and 94% in Germany.

In 2014 in Barcelona, the Spanish testing laboratory accredited by the Empresa Nacional de Acreditación (ENAC) FUTTEC S.L carried out, with a double monochromator spectrometer calibrated by the Centro Superior de Investigaciones Científicas (CSIC), different irradiance measurements on the blue ranges of mobile phones, laptops, and indoor lights in W/m2 compared to the same ranges within the blue range of UVI 6 and UVI 9.

The measurements were made at the distances that the electronic devices are located from our eyes. Figure 3 shows a graph of the ultraviolet index (UVI) measurements (around five) given by the Department of Astronomy and Meteorology of the Faculty of Physics at the University of Barcelona. The maximum irradiance was observed around 480 nm.

**Figure 3.** Several solar spectral distributions provided by the Faculty of Physics of the University of Barcelona [54].

These results were made public at the Congress of the General Council of the Official Associations of Pharmacists of Spain (CGCOF). Below are the results of the irradiance measurements of 10 nm between 400 nm and 600 nm performed by the FUTTEC test laboratory including:


In Figure 4, the green line represents measurements on a computer screen in a workroom, where the windows facing the street are very close. This is why the measured irradiance is superior to the irradiances of smartphones, computers, mobile phones, and LEDs, and similar in shape to the graphics of sunlight.

Escofet and Bará [55] show the analysis of two computer screens and two smartphones. The irradiance results from the computers are around 450 nm of 4 <sup>×</sup> 10−<sup>3</sup> W/m2, and those from the two smartphones around 450 nm are 6–7 <sup>×</sup> <sup>10</sup>−<sup>4</sup> <sup>W</sup>/m2. In their article, they show the absorption of different filters to be placed in front of the screens to reduce the irradiance in the blue range and recommend their use.

In 2018, new measurements were made in an optics laboratory on an optical bench in total darkness with a double monochromator spectrometer from FUTTEC S.L. calibrated by the CSIC. The measured electronic equipment belonged to students studying optics who were asked to give their electronic equipment a blue background with maximum luminosity. The measurements were taken at the distance at which they said they would put the equipment in place to use it. A nanometer by nanometer scan was performed from 350 to 500 nm to analyze the area in the blue range, as well as the irradiance peak. Table 1 shows the irradiance and peak light results from these measurements.

**Figure 4.** Comparison of the irradiance of artificial light sources with that of the sun. The 400–500 nm irradiance of electronic equipment for personal use, indoor lighting, and solar ultraviolet index (UVI) (modified vertical axis scale). Authors' own.


