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Author |
Hale, J.D.; Davies, G.; Fairbrass, A.J.; Matthews, T.J.; Rogers, C.D.F.; Sadler, J.P. |
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Title |
Mapping lightscapes: spatial patterning of artificial lighting in an urban landscape |
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Journal Article |
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Year |
2013 |
Publication |
PloS one |
Abbreviated Journal |
PLoS One |
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Volume |
8 |
Issue |
5 |
Pages |
e61460 |
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Keywords |
*Cities; England; Environmental Pollution; Geographic Mapping; Humans; Light; *Lighting; Photography; Urban Population; *Urbanization |
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Abstract |
Artificial lighting is strongly associated with urbanisation and is increasing in its extent, brightness and spectral range. Changes in urban lighting have both positive and negative effects on city performance, yet little is known about how its character and magnitude vary across the urban landscape. A major barrier to related research, planning and governance has been the lack of lighting data at the city extent, particularly at a fine spatial resolution. Our aims were therefore to capture such data using aerial night photography and to undertake a case study of urban lighting. We present the finest scale multi-spectral lighting dataset available for an entire city and explore how lighting metrics vary with built density and land-use. We found positive relationships between artificial lighting indicators and built density at coarse spatial scales, whilst at a local level lighting varied with land-use. Manufacturing and housing are the primary land-use zones responsible for the city's brightly lit areas, yet manufacturing sites are relatively rare within the city. Our data suggests that efforts to address light pollution should broaden their focus from residential street lighting to include security lighting within manufacturing areas. |
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School of Geography, Earth and Environmental Sciences, The University of Birmingham, Birmingham, West Midlands, United Kingdom. j.hale@bham.ac.uk |
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1932-6203 |
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PMID:23671566; PMCID:PMC3646000 |
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no |
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IDA @ john @ |
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209 |
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Author |
Inger, R.; Bennie, J.; Davies, T.W.; Gaston, K.J. |
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Title |
Potential biological and ecological effects of flickering artificial light |
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Journal Article |
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Year |
2014 |
Publication |
PloS one |
Abbreviated Journal |
PLoS One |
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Volume |
9 |
Issue |
5 |
Pages |
e98631 |
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Keywords |
flickering; artificial light; biology |
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Abstract |
Organisms have evolved under stable natural lighting regimes, employing cues from these to govern key ecological processes. However, the extent and density of artificial lighting within the environment has increased recently, causing widespread alteration of these regimes. Indeed, night-time electric lighting is known significantly to disrupt phenology, behaviour, and reproductive success, and thence community composition and ecosystem functioning. Until now, most attention has focussed on effects of the occurrence, timing, and spectral composition of artificial lighting. Little considered is that many types of lamp do not produce a constant stream of light but a series of pulses. This flickering light has been shown to have detrimental effects in humans and other species. Whether a species is likely to be affected will largely be determined by its visual temporal resolution, measured as the critical fusion frequency. That is the frequency at which a series of light pulses are perceived as a constant stream. Here we use the largest collation to date of critical fusion frequencies, across a broad range of taxa, to demonstrate that a significant proportion of species can detect such flicker in widely used lamps. Flickering artificial light thus has marked potential to produce ecological effects that have not previously been considered. |
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Environment and Sustainability Institute, University of Exeter, Penryn, Cornwall, United Kingdom |
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1932-6203 |
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PMID:24874801; PMCID:PMC4038456 |
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IDA @ john @ |
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237 |
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Aubé, M.; Roby, J.; Kocifaj, M. |
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Title |
Evaluating potential spectral impacts of various artificial lights on melatonin suppression, photosynthesis, and star visibility |
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Journal Article |
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Year |
2013 |
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PloS one |
Abbreviated Journal |
PLoS One |
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8 |
Issue |
7 |
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e67798 |
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Keywords |
Humans; *Light; Lighting/methods; Melatonin/*metabolism; Photosynthesis/*radiation effects; Plant Development/radiation effects; blue light; circadian disruption |
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Artificial light at night can be harmful to the environment, and interferes with fauna and flora, star visibility, and human health. To estimate the relative impact of a lighting device, its radiant power, angular photometry and detailed spectral power distribution have to be considered. In this paper we focus on the spectral power distribution. While specific spectral characteristics can be considered harmful during the night, they can be considered advantageous during the day. As an example, while blue-rich Metal Halide lamps can be problematic for human health, star visibility and vegetation photosynthesis during the night, they can be highly appropriate during the day for plant growth and light therapy. In this paper we propose three new indices to characterize lamp spectra. These indices have been designed to allow a quick estimation of the potential impact of a lamp spectrum on melatonin suppression, photosynthesis, and star visibility. We used these new indices to compare various lighting technologies objectively. We also considered the transformation of such indices according to the propagation of light into the atmosphere as a function of distance to the observer. Among other results, we found that low pressure sodium, phosphor-converted amber light emitting diodes (LED) and LED 2700 K lamps filtered with the new Ledtech's Equilib filter showed a lower or equivalent potential impact on melatonin suppression and star visibility in comparison to high pressure sodium lamps. Low pressure sodium, LED 5000 K-filtered and LED 2700 K-filtered lamps had a lower impact on photosynthesis than did high pressure sodium lamps. Finally, we propose these indices as new standards for the lighting industry to be used in characterizing their lighting technologies. We hope that their use will favor the design of new environmentally and health-friendly lighting technologies. |
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Departement de physique, Cegep de Sherbrooke, Sherbrooke, Quebec, Canada. martin.aube@cegepsherbrooke.qc.ca |
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1932-6203 |
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PMID:23861808; PMCID:PMC3702543 |
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IDA @ john @ |
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282 |
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Chellappa, S.L.; Steiner, R.; Blattner, P.; Oelhafen, P.; Gotz, T.; Cajochen, C. |
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Non-visual effects of light on melatonin, alertness and cognitive performance: can blue-enriched light keep us alert? |
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Journal Article |
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2011 |
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PloS one |
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PLoS One |
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6 |
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1 |
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e16429 |
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Circadian Rhythm/radiation effects; Cognition/*radiation effects; Color; Cross-Over Studies; Fluorescence; Humans; *Light; Male; Melatonin/*radiation effects; Reaction Time/*radiation effects; Young Adult; blue light |
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BACKGROUND: Light exposure can cascade numerous effects on the human circadian process via the non-imaging forming system, whose spectral relevance is highest in the short-wavelength range. Here we investigated if commercially available compact fluorescent lamps with different colour temperatures can impact on alertness and cognitive performance. METHODS: Sixteen healthy young men were studied in a balanced cross-over design with light exposure of 3 different light settings (compact fluorescent lamps with light of 40 lux at 6500K and at 2500K and incandescent lamps of 40 lux at 3000K) during 2 h in the evening. RESULTS: Exposure to light at 6500K induced greater melatonin suppression, together with enhanced subjective alertness, well-being and visual comfort. With respect to cognitive performance, light at 6500K led to significantly faster reaction times in tasks associated with sustained attention (Psychomotor Vigilance and GO/NOGO Task), but not in tasks associated with executive function (Paced Visual Serial Addition Task). This cognitive improvement was strongly related with attenuated salivary melatonin levels, particularly for the light condition at 6500K. CONCLUSIONS: Our findings suggest that the sensitivity of the human alerting and cognitive response to polychromatic light at levels as low as 40 lux, is blue-shifted relative to the three-cone visual photopic system. Thus, the selection of commercially available compact fluorescent lights with different colour temperatures significantly impacts on circadian physiology and cognitive performance at home and in the workplace. |
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Centre for Chronobiology, Psychiatric Hospital of the University of Basel, Basel, Switzerland |
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1932-6203 |
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PMID:21298068; PMCID:PMC3027693 |
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IDA @ john @ |
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286 |
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Taillard, J.; Capelli, A.; Sagaspe, P.; Anund, A.; Akerstedt, T.; Philip, P. |
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Title |
In-car nocturnal blue light exposure improves motorway driving: a randomized controlled trial |
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Journal Article |
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Year |
2012 |
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PloS one |
Abbreviated Journal |
PLoS One |
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7 |
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10 |
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e46750 |
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Adult; *Automobile Driving; Caffeine/pharmacology; Coffee/chemistry; Cross-Over Studies; Double-Blind Method; Fatigue/*prevention & control; Humans; Light; Male; Middle Aged; *Photic Stimulation; Placebos; Psychomotor Performance/drug effects/radiation effects; Reproducibility of Results; Sleep Deprivation; Sleep Stages/radiation effects; Wakefulness/drug effects/physiology/*radiation effects; blue light |
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Prolonged wakefulness greatly decreases nocturnal driving performance. The development of in-car countermeasures is a future challenge to prevent sleep-related accidents. The aim of this study is to determine whether continuous exposure to monochromatic light in the short wavelengths (blue light), placed on the dashboard, improves night-time driving performance. In this randomized, double-blind, placebo-controlled, cross-over study, 48 healthy male participants (aged 20-50 years) drove 400 km (250 miles) on motorway during night-time. They randomly and consecutively received either continuous blue light exposure (GOLite, Philips, 468 nm) during driving or 2*200 mg of caffeine or placebo of caffeine before and during the break. Treatments were separated by at least 1 week. The outcomes were number of inappropriate line crossings (ILC) and mean standard deviation of the lateral position (SDLP). Eight participants (17%) complained about dazzle during blue light exposure and were removed from the analysis. Results from the 40 remaining participants (mean age +/- SD: 32.9+/-11.1) showed that countermeasures reduced the number of inappropriate line crossings (ILC) (F(2,91.11) = 6.64; p<0.05). Indeed, ILC were lower with coffee (12.51 [95% CI, 5.86 to 19.66], p = 0.001) and blue light (14.58 [CI, 8.75 to 22.58], p = 0.003) than with placebo (26.42 [CI, 19.90 to 33.71]). Similar results were found for SDLP. Treatments did not modify the quality, quantity and timing of 3 subsequent nocturnal sleep episodes. Despite a lesser tolerance, a non-inferior efficacy of continuous nocturnal blue light exposure compared with caffeine suggests that this in-car countermeasure, used occasionally, could be used to fight nocturnal sleepiness at the wheel in blue light-tolerant drivers, whatever their age. More studies are needed to determine the reproducibility of data and to verify if it can be generalized to women. Trial registration: ClinicalTrials.gov NCT01070004. |
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University of Bordeaux, Sommeil, Attention et Neuropsychiatrie, USR 3413, Bordeaux, France. jack.taillard@gmail.com |
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1932-6203 |
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PMID:23094031; PMCID:PMC3477137 |
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IDA @ john @ |
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347 |
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