Reddening the nighttime environment: Use of <scp>PC</scp> ‐amber <scp>LED</scp> lighting

Abstract The introduction of artificial light is changing the nighttime environment over large areas of the Earth, disrupting natural light regimes in terms of the occurrence, timing and forms of light. Because of the centrality of those natural light regimes to many biological processes, artificial light at night (ALAN) has quite pervasive environmental impacts, including on individual organisms, populations, communities and ecosystems. The widespread and ongoing introduction of Phosphor‐converted white (PC‐white) LEDs has particularly accelerated the disruption of natural light regimes and exacerbated many of the environmental impacts. In large part this is because of the resultant increased emissions in the blue part of the spectrum, to which key biological processes are especially sensitive. The use of Phosphor‐converted amber (PC‐amber) LEDs, with emissions in the blue much reduced and therefore in effect reddened compared with PC‐white LEDs, has been widely championed as a means of reducing (albeit not eliminating) these environmental impacts. Here we argue that, as things stand, the evidence for the efficacy of PC‐amber LEDs in such reductions is quite limited and that these lamps should not be seen as a panacea for the environmental impacts of ALAN. In particular, PC‐amber LEDs can still have substantial blue emissions and thus have greater biological impacts than might otherwise be assumed, especially if they are used at higher intensities. Other lighting options, which have thus far received little attention, may be more advantageous, especially if their availability improves and thus results in associated price reductions. However, more basic ways of limiting ALAN should remain high priorities, such as removing unnecessary lights, dimming lighting, improving shielding and part‐night lighting. Practical implication . Although they can provide benefits, caution should be exercised in the widespread use of PC‐amber LEDs as an environmentally sensitive solution to the installation of outdoor lighting.