In the previous posts, we have explored the negative implications of light on individuals, society and on the biodiversity in our environment. Before delving into the various types of policies that can be taken to reduce the impacts of light pollution, it is important to recognise the various types of lighting that contribute least to light pollution. The three main criteria determining how pollutive a light source is dependent on:
- the colour temperature of the light
- the type of light fixtures used
- presence of technology that varies light output over time
Firstly, the colour temperature of light is a measurement of how warm or cool light is, measured by the unit Kelvin (K). As a general rule of thumb, anything 3000K or lower is referred to as warm light, whereas anything above 4000k is referred to as cool light. For reference, the typical incandescent light bulbs that we have in our homes have a colour temperature of about 2500-2700K and outdoor lighting and security lights found along pavements are generally 4500-6000K.
Figure 1: Colour temperature of light (Kluska, 2020)
According to International Dark-Sky Association, light with colour temperatures below 3000K greatly helps in reducing light pollution – warm lights scatter less in the atmosphere and produce less skyglow. Warmer lights are also less likely to affect human vision, wildlife reproduction and behaviours as compared to blue lighting as it has less glare.
Although, it might not be wholly practical to install yellow lights in every corner of our house and in every corner of the city, as each type of light has its own uses and benefits. Yellow light offers mental stability and relaxation and could cause one to feel sleepy easily. On the other hand, white light (in moderation) is proven to be better for concentration. Hence, white lights are often found along roads or in areas requiring surveillance as they are brighter and can help to deter accidents and crime. Different colours of light are also often used for decorative purposes, for instance in light installations along Orchard Road during festivities, which has since become an attraction for many. Dimming the lights on these festivity lightings may hence not be as practical as well and should be done depending on individual setting and location.
Look around your house – what type of bulbs do you use? Observe our streets as you head out – what type of lighting is used in what circumstances and why?
References:
International Dark-Sky Association. (n.d.). Light Pollution Solutions. https://www.darksky.org/light-pollution/light-pollution-solutions/
Kluska, E. (2020). Choosing the Right Color Temperature for Your Home – The Lighting Blog. [online] Prolighting.com. Available at: https://www.prolighting.com/blog/2020/06/16/choosing-the-right-color-temperature-for-your-home/
Lumen Now Staff (2020). White Light vs. Yellow Light: Which is Better for Eyes When Reading & Studying. [online] Lumen Now. Available at: https://lumennow.org/reading-light-white-or-yellow/