Selected Blue Light Characteristics of Various Outdoor Lighting Sources at Equivalent Lumen Output

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Table 1 below lists various sources used in street and area lighting (among other applications) along with selected characteristics related to their spectral content, normalized for equivalent lumen output. The table was updated in June 2017 from an earlier version to increase the number of LED samples on which the corresponding data ranges are based (see Table 2). Data for each source includes a measured correlated color temperature (CCT), the calculated percentage of radiant power contained in "blue wavelengths" (defined here from the literature related to sky glow as wavelengths between 405 and 530 nanometers [nm]), and the corresponding scotopic and melanopic multipliers that are shown relative to a high-pressure sodium (HPS) baseline due to its predominance in the existing outdoor lighting market.

Table 1: Selected blue light characteristics of various outdoor lighting sources at equivalent lumen output.

RowLight sourceLuminous Flux (lm)CCT (K)% Blue* Relative Scotopic Potential Relative Melanopic Potential**
APC White LED1000270015% - 21%1.74 - 2.331.90 - 2.82
BPC White LED1000300018% - 25%1.88 - 2.462.09 - 3.06
CPC White LED1000350022% - 28%2.04 - 2.542.34 - 3.25
DPC White LED1000400026% - 33%2.11 - 2.772.36 - 3.64
EPC White LED1000450032% - 35%2.39 - 2.942.83 - 3.95
FPC White LED1000500035% - 40%2.61 - 3.433.22 - 4.69
GPC White LED1000570039% - 45%2.75 - 3.393.42 - 4.62
HPC White LED1000650043% - 48%3.12 - 3.974.10 - 5.87
INarrowband Amber LED100016060%0.360.12
JLow Pressure Sodium100017180%0.340.10
KPC Amber LED100018721%0.700.42
LHigh Pressure Sodium100019599%0.890.86
MHigh Pressure Sodium1000204110%1.001.00
NMercury Vapor1000692436%2.332.47
OMercury Vapor1000403735%2.132.51
PMetal Halide1000314524%2.162.56
QMetal Halide1000400233%2.533.16
RMetal Halide1000404135%2.843.75
SMoonlight†1000468129%3.334.56
TIncandescent1000281211%2.212.72
UHalogen1000293413%2.282.81
VF32T8/830 Fluorescent1000294020%2.022.29
WF32T8/835 Fluorescent1000348026%2.372.87
XF32T8/841 Fluorescent1000396930%2.583.18

* Percent blue calculated according to LSPDD: Light Spectral Power Distribution Database, http://galileo.graphycs.cegepsherbrooke.qc.CA/app/en/home.

** Melanopic content calculated according to CIE Irradiance Toolbox, http://files.cie.co.at/784_TN003_Toolbox.xls (download), 2015.

† Moonlight CCT provided by Telelumen, LLC.

The ranges listed for the LED properties reflect the fact that various products often differ from one another in terms of their precise spectral content, even when binned together in the same nominal CCT, and each CCT bin listed in the table contains numerous product samples. The exact number of samples in each bin ranges from 20 (for 5700 K) to 162 (for 3000 K), with others falling in between (457 samples in all; see Table 2). Conventional light sources are all represented by single values though they would likewise be more accurately characterized by a range (albeit much narrower than LED). 

Table 2: Number of LED products underlying the data ranges shown for each CCT bin in Table 1.

CountRowLight sourceLuminous Flux (lm)CCT (K)
59APC White LED10002700
162BPC White LED10003000
53CPC White LED10003500
51DPC White LED10004000
36EPC White LED10004500
44FPC White LED10005000
20GPC White LED10005700
32HPC White LED10006500

Most importantly, performing a calculation with these values only provides an idea of the relative potential to cause health or other impacts, rather than detailing any actual impacts likely to occur. Impacts are critically related to additional factors such as intensity, length of exposure, and other exogenous variables that are not represented in the table.

Nevertheless, the potential influence of blue wavelengths is immediately evident in all "white light" sources containing them. In addition, as demonstrated by the relative properties displayed by conventional lighting sources in the table, the blue light issues that have been raised in recent debate are clearly nothing new to our lighted environment. What is new is our increased understanding of their potential influence regarding human and environmental health issues, as the related research has evolved. Much work remains to put any associated potential risk into a realistic context, however.