Summary
At the low illuminance levels typical of road lighting (1–100 lx in mesopic range), circadian stimulus values for most light sources fall at or below the threshold of CS=0.05, suggesting circadian disruption is not a major concern for roadway applications. Lighting designers can therefore prioritize mesopic efficiency (S/P ratio optimization) when selecting road light sources, as this strategy is largely compatible with minimizing unwanted circadian activation.
Key Findings
- EML values for road lighting sources remain below 50 EML under mesopic vision conditions (photopic illuminance 1–100 lx).
- CS values for most road lighting sources fall at or below the circadian threshold of 0.05, indicating negligible circadian stimulus.
- S/P ratio correlates more strongly with EML and CS than correlated color temperature (CCT) does, making S/P ratio a better proxy for circadian impact in road lighting selection.
- Several light sources were identified that simultaneously achieve high mesopic efficiency and low CS, offering a compatible optimization pathway for road lighting.
Categories
The Science of Light: Analyzes melanopic EDI (EML), circadian light (CLA), and circadian stimulus (CS) metrics alongside S/P ratios across mesopic illuminance levels relevant to road lighting.
Sleep & Circadian Health: Evaluates the practical significance of circadian disruption from road lighting exposure under mesopic vision conditions.
Author(s)
M Li, P Wu, J Ding, Q Yao, J Ju
Publication Year
2020
Number of Citations
9
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