Climate Change, Fluorescent Lighting, and Eye Disease: A Little Too Light on the Science

Abstract

Walls et al. are undoubtedly well intentioned, but ill informed on lighting technologies and practices. Consequently statements in their recent article on fluorescent lighting and eye disease were technically incorrect and unnecessarily alarming to the public.1 We offer some corrections: high-intensity discharge (HID) lamps are typically more efficacious than fluorescent ones and about equally so when comparing similar wattages; light-emitting diodes (LEDs) appear brighter than fluorescent lamps—brightness is dimensionally equivalent to luminance, not total luminous flux; fluorescent lamps are available in a range of correlated color temperatures (CCTs) from 2700 K to 6500 K and above. The most popular ranges of CCTs used in the United States are between 3500 K and 4100 K for commercial and industrial use and between 2700 K to 3000 K for residential use, the latter figure being mainly from compact fluorescent lamps (CFLs); fluorescent lamps are operated using a ballast that drives one or multiple (up to four) lamps. Running multiple lamps per ballast improves system efficacy, but does not reduce flicker since most ballasts today operate the lamps at very high frequencies (> 20 kHz); CCT is completely independent of actinic dangers from light sources because a CCT designation is not unambiguously related to the spectral power distribution of the source. Indeed it is dangerously misleading to characterize actinic effects in terms of CCT; and there is no scientific consensus that lamps with higher CCTs improve concentration. Although this letter cannot cover all of the half-truths in the article by Walls et al., we do strongly recommend that the authors, as well as interested readers, familiarize themselves with the potential health risks of optical radiation from fabricated and natural light sources. Towards this goal, we suggest the following resources. In the first resource, Bullough describes retinal damage from prolonged viewing of intense short-wavelength radiation (i.e., blue light hazard).2 In the second one, Bergman et al. offer quantitative evaluations of the ultraviolet (UV) actinic dangers from common lamps.3 Finally, the current standards for optical radiation safety provide key references to the literature.4,5