This report presents a comprehensive investigation of glare risks for vehicle drivers on

the E4 road between Linköping and Södertälje, specifically caused by train headlights on

the Ostlänken railway in a proposed future expansion.

Based on simulations, empirical studies, applicable regulations, and previous research,

we propose that threshold values for both veiling luminance (LV) and illuminance (E) at

the driver’s eye should be considered when assessing glare risks. As indicative threshold

values, LV < 2 cd/m² in combination with E < 0.3 lx for incidence angles (θ) < 10° are

proposed. In addition, three risk levels have been defined based on the maximum

distance (Dmax) between trains and road vehicles at which glare may cause discomfort or

visual impairment. In the analysis, Dmax = 500 m is used to represent a high risk level,

Dmax = 600 m a low risk level, and Dmax = 800 m a very low risk level. The selected Dmax

levels represent more or less conservative assumptions regarding the distances at which

glare may be considered relevant and potentially constitute a safety concern.

By using light distributions from measured train headlights, we have modelled the

lighting conditions at the driver’s eye for different relative positions between trains and

road vehicles. The analysis shows that the length of glare shielding required to limit glare

to acceptable levels approximately corresponds to the section of the railway over which

train headlights may cause glare. For Dmax = 500 m, slightly more than 4 km of glare

shielding is required, for Dmax = 600 m slightly more than 6 km and for Dmax = 800 m

approximately 9,5 km. Road lighting can reduce the risk of glare but is unlikely to

eliminate the need for glare shielding in the most critical sections.

The assessment of accident risk and glare is based on a review of traffic accidents

involving reported personal injuries associated with glare in the Swedish Transport

Agency’s accident reporting system STRADA for the years 2010–2024, combined with

information from previously conducted questionnaire studies and analyses of accident

statistics. The number of accidents that can be linked to glare is small compared with the

total number of accidents, although some degree of underreporting is likely. Single-

vehicle accidents are the most common accident type, while pedestrian collisions pose

the greatest risk of serious injuries and fatalities.

The project has contributed increased knowledge on when mitigation measures should

be implemented to avoid excessively high glare from oncoming vehicles and support

safer infrastructure design. While the study addresses glare affecting road vehicle

drivers caused by headlights from oncoming trains on adjacent railway lines, parts of

the results may be applicable more generally.

Wearable light loggers enable the assessment of personal light exposure in real-world settings, providing insight into both visual and non-visual effects of light on human physiology. This paper presents initial results from the Swedish cohort of the MeLiDos multi-center field study. Seventeen participants wore spectrally resolved light loggers at multiple body locations for one week. We examine inter-individual variability in light exposure, compare measurements across sensor positions, and analyze photopic illuminance and melanopic equivalent daylight illuminance (m-EDI). Results show strong seasonal and inter-individual variability, systematic differences between logger positions, and pronounced diurnal variation in the melanopic/photopic (m-EDI/Ev) ratio. These findings suggest that wearable light logging is a viable approach in field studies, provided that methodological challenges are carefully addressed

The phantom array effect (PAE) has been widely investigated, but data are still insufficiently consistent to accurately predict the visibility of the PAE. One of the most critical steps towards a visibility measure is the temporal contrast threshold/sensitivity function. To determine this function, we experimentally measured the visibility threshold of the PAE at various frequencies. Participants were instructed to make 54.5° saccades in the dark across a thin light source, subtending a visual angle of 0.2° (horizontally) × 10° (vertically), with a luminance of 50 cd m−2. Their task was to indicate in which of two sequentially presented stimuli they observed the PAE, where one stimulus was the reference driven with a direct current and one was the test stimulus, sinusoidally modulated over time. The QUEST+ method was used to change the modulation depth in the test stimulus. The results revealed a bandpass-shaped sensitivity curve of the PAE, with a peak at about 600 Hz. About 70% of the 22 participants had a peak sensitivity between a modulation depth of 0.04 and 0.13, and 65% of the 22 participants had a peak frequency between 460 Hz and 700 Hz.

Traffic safety during nighttime remains a critical concern, particularly for vulnerable road users such as pedestrians and cyclists. This study investigates the role of glare from headlamps and other artificial lighting as a contributing factor in traffic accidents using Swedish crash data from the STRADA database (2010-2024). A total of 549 injury-related accidents were identified as associated with nighttime glare. The analysis reveals that while glare-related accidents constitute a small fraction of overall traffic incidents (approximately 37 per year or 0.2% of all nighttime accidents), certain patterns emerge: collisions involving pedestrians carry the highest risk of severe outcomes, single-vehicle incidents are the most frequent, and wildlife collisions show the highest proportional link to glare. These findings indicate that, although uncommon, glare can contribute to serious accidents, particularly for vulnerable road users, and underscore the importance of appropriate headlamp usage and glare mitigation strategies during nighttime driving

Light exposure profoundly influences human health, regulating circadian rhythms and impacting wakefulness and sleepiness. Estimating the effects of light exposure under everyday conditions requires personal, wearable light logging and dosimetry approaches. This article introduces the MeLiDos Project (2023–2026), supported by the European Association of National Metrology Institutes (EURAMET). The project’s first branch defines quality indices and calibration standards for wearable light loggers, adapting existing metrological standards to their smaller size and distinct purpose in the field rather than the laboratory. The second branch develops a software ecosystem, including the open-source R software package LightLogR, designed to manage the increasing volume of data, ensuring reusability, accessibility and interoperability of data. The third branch explores the potential of spatially resolved light dosimetry. The MeLiDos Project anticipates advancements in wearable light metrology, paving the way for optimizing human health and well-being through wearable light logging technologies. 

Light profoundly impacts many aspects of human physiology and behaviour, including the synchronization of the circadian clock, the production of melatonin, and cognition. These effects of light, termed the non-visual effects of light, have been primarily investigated in laboratory settings, where light intensity, spectrum and timing can be carefully controlled to draw associations with physiological outcomes of interest. Recently, the increasing availability of wearable light loggers has opened the possibility of studying personal light exposure in free-living conditions where people engage in activities of daily living, yielding findings associating aspects of light exposure and health outcomes, supporting the importance of adequate light exposure at appropriate times for human health. However, comprehensive protocols capturing environmental (e.g., geographical location, season, climate, photoperiod) and individual factors (e.g., culture, personal habits, behaviour, commute type, profession) contributing to the measured light exposure are currently lacking. Here, we present a protocol that combines smartphone-based experience sampling (experience sampling implementing Karolinska Sleepiness Scale, KSS ratings) and high-quality light exposure data collection at three body sites (near-corneal plane between the two eyes mounted on spectacle, neck-worn pendant/badge, and wrist-worn watch-like design) to capture daily factors related to individuals’ light exposure. We will implement the protocol in an international multi-centre study to investigate the environmental and socio-cultural factors influencing light exposure patterns in Germany, Ghana, Netherlands, Spain, Sweden, and Turkey (minimum n = 15, target n = 30 per site, minimum n = 90, target n = 180 across all sites). With the resulting dataset, lifestyle and context-specific factors that contribute to healthy light exposure will be identified. This information is essential in designing effective public health interventions. 

The spectral distribution is a fundamental property of non-monochromatic optical radiation. It is commonly used in research and practical applications when studying how light interacts with matter and living organisms, including humans. In the field of lighting, misconceptions about the spectral distribution of light are responsible for unfounded claims, which pervade the scientific and technical communities. Starting from the definition of the spectral distribution, this paper describes the ambiguities and errors associated with a purely graphical analysis of the spectral distribution. It also emphasizes the importance of considering the particle nature of light in research involving both visual and non-visual effects, which implies using the spectral distribution expressed in the photon system of units, a system that has been seldom used in lighting research for historical reasons. The authors encourage lighting engineers and researchers to determine which system is best suited to their work and then proceed with the correct use of spectral distributions and of spectral weighting functions for applications involving optical radiation. © The Chartered Institution of Building Services Engineers 2024.

The widespread use of electric lighting has revolutionised society but brought unintended consequences, notably light pollution, impacting ecosystems and human circadian rhythms. Concerns about anthropogenic light at night (ALAN) have prompted innovative solutions, such as spectral tuning of light sources. In Europe, a recent focus involves the enforcement of red light in outdoor settings to minimise ALAN’s impact, particularly on bats. This mini review synthesises literature to provide an overview of the advantages and disadvantages of the use of red light outdoors. There is a need for further examination of the potential ecological consequences of red light, considering challenges in lighting design functionality and broader impacts on diverse species.

Insects play a critical role in providing numerous ecosystem services. However, insect diversity and biomass have been declining dramatically, with artificial light being suggested as a contributing factor. Despite the importance of understanding the dose–effect responses of insects to light emissions, these responses have been rarely studied. We examined the dose–effect responses of the greater wax moth (Galleria mellonella L.) to different light intensities (14 treatments and a dark control) by observing their behavioural responses in a light-tight box equipped with a LED light source (4070 K) and infrared cameras. Our findings reveal dose–effect responses to light, as the frequency of walking on the light source increased with higher light intensity. Additionally, moths exhibited jumps in front of the light source and jump frequency increased with light intensity. No direct flight-to-light behaviour or activity suppression in response to light was observed. Based on our analysis of the dose–effect responses, we identified a threshold value of 60 cd/m2 for attraction (walking on the light source) and the frequency of jumps. The experimental design in this study offers a valuable tool for investigating dose–effect relationships and behavioural responses of various species to different light levels or specific light sources. © 2023, The Author(s).

Circular economy is becoming an important topic for lighting design, research, and industry. Recent legislation, like the EU's ecodesign regulation, has established circularity, reparability, and recyclability as requirements for the industry. This article investigates what happens at the end-of-life stages of lighting products through questionnaires and interviews conducted with experts in Sweden and France. The focus is on understand the impact of the new EU requirements on industrial practice in France and Sweden. Moreover, the article provides ideas for practical improvement of both product recyclability and waste handling of luminaires and light sources.