Blue light content is a critical factor as it has been shown to have a significant impact on the circadian rhythms and behaviours of humans, plants, and wildlife. It is increasingly the focus of attention for local authorities, municipalities, policy makers and legislators.

Communities across the world are grappling with how to reduce the impact of artificial light at night and municipalities and governments are addressing the issues of light pollution and wildlife impacts with lighting ordinances that proscribe both the design of light fixtures and the nature of the light that they emit. Some local authorities –such as Maui in Hawaii – even limit blue to under 2 per cent of new exterior light.

Designers often want warm colour temperatures of 3000K and 1800K for outdoor applications but these can still have relatively high percentages of blue light content and cannot come close to achieving less than 2 per cent. Phosphor-converted amber, or a 3000K white LED and an amber filter or amber optics are options, but both have significant downsides.