Reply by SMS Desmond Lee, in response to Adjournment Motion by MP Dr Tan Wu Meng on “Changing the Colours of Night: Co-ordinating LED Illumination in Our National Infrastructure”

Feb 6, 2017

Madam Speaker, I agree with Dr Tan Wu Meng that night lighting has an impact on the everyday lives of Singaporeans. Our lighting must be:

First, functional. From drivers on our expressways to passers-by along our HDB estate corridors, night lighting must be calibrated to suit their different needs.

Second, it must be aesthetically pleasing. It should positively shape how we perceive and interact with our estates and public spaces.

Third, it has to be safe. This is important given how pervasive night lighting is in a dense built-up city like Singapore.

To achieve this, one of the specifications we take into account is the light colour. Those of you who have bought fluorescent or LED lights will know that they generally come in three colours as Dr Tan had described: “warm white”, “pure white” and “cool white”.

i) “Warm white” has the least amount of blue-light, giving it a yellow hue and a colour temperature of about 3000 Kelvin;

ii) Pure white” has a more balanced mix of blue-light, giving it a natural daylight feel and a colour temperature of 4000 Kelvin; while

iii)“Cool white” has the highest amount of blue-light, resulting in a harsh white colour and a colour temperature of 6000 Kelvin.

Light colour is important for both functionality and aesthetics.

- For our street lighting, LTA is moving towards “pure white” because it offers drivers a high colour contrast, allowing them to see better at night.

- In our new HDB developments, light fittings at common areas (such as corridors) also use “pure white” – but for a different reason: previous feedback garnered from residents indicated that “warm white” was too dim for HDB estates.

Light colour can affect safety too, as Dr Tan rightly pointed out. I have explained how LTA uses light colour to improve road safety at night for drivers, pedestrians.

Dr Tan has cited several reports which advise minimising the amount of blue-light for health reasons. Based on these reports, he has suggested we use “warm white” in our HDB common areas and LTA street lighting. These reports make two broad points:

- First, they state that long term or high intensity exposure to blue-light can damage the retina of the human eye.
- Second, they highlight that exposure to any light at night – especially blue-light – can affect our sleep cycles by suppressing the production of a hormone called melatonin, and affect our circadian rhythm or body clock¹. This has been linked to impaired daytime functioning and obesity.

I would like to clarify that care has been taken by government agencies to ensure that the lighting installed in public places do not cause harm to the human eye. The first point about potential damage to the retina of the human eye is not a significant concern in Singapore, given our regulations.

- Lighting in our HDB common areas and LTA street lighting follow the globally-recognised International Electrotechnical Commission (IEC) standards.These spell out technical and safety requirements for lighting – including the safety limit for exposure to white light.

- Indeed, the same report by the Swiss Federal Office of Public Health states that “commercial LED lamps represent no health risk when used correctly²” in terms of the risk to human retina safety.

On the second claim on the impact of blue-light on melatonin and our sleep cycles, as Dr Tan pointed out, there is no medical consensus on the issue as yet.

- The reports do not rule out the use of “pure white” lighting in street lighting or in public spaces like our HDB common areas.

- And the specific implications of the reports’ findings on our HDB common areas and LTA street lighting are as yet unclear.

i) For example, the Harvard Medical School’s Harvard Health Letter is based on studies which exposed people to blue-light for 6.5 hours or longer.

ii) The exposure of many Singaporeans’ to HDB corridors and LTA street lighting is much shorter.

Apart from changing the colour of all our lighting, there may be other ways to address this issue. Indeed, one of the possible solutions mentioned by the American Medical Association is dimming LED lighting during off-peak periods.

i) We have in fact already installed LED lighting with motion sensors along staircases for all BTO projects launched since 2014, and

ii) We are testing out sensor-controlled smart lighting in the common areas of Punggol Northshore estates.

iii) Not only will this make our HDB estates more energy efficient, it would also minimise ambient blue-light at night.

- Ultimately, we must ensure that our lighting remains functional, aesthetically pleasing and safe. The light colours of HDB common areas and LTA street lamps are carefully selected to meet the functional, safety and aesthetic needs of Singaporeans. We should only decide how best to enhance our lighting after further study on the appropriate length and intensity of blue-light exposure at night has been done.

This notwithstanding, I agree with Dr Tan that it is not too early for us to be thinking about the long term implications of these reports on the health and safety of Singaporeans.

- We will continue to keep a close watch on the evolving research on this area.

- HDB will also take up Dr Tan’s suggestion to study how to vary lighting levels based on different colours of LED lights. This will allow us to better decide on the appropriate light colours in different settings – be it for functional or aesthetic reasons.

On its part, LTA will continue to use “pure white” lighting for expressways and major arterial roads for road safety reasons because of the greater colour contrast.

- In the meantime, because street lamps use high intensity lighting, LTA will study whether it is feasible to use “warm white” lighting for street lamps on minor roads – especially those located in residential estates.

Madam Speaker, the scientific research into lighting is evolving, and new lighting solutions will come on the market. We will continue to take steps to find better ways to colour the night, to keep our city vibrant and safe.

1: Melatonin is produced by the pineal gland in the brain. It helps control a person’s daily sleep-wake cycles. A person’s body’s internal clock (also known as circadian rhythm) influences how much melatonin the pineal gland makes, and so does the amount of light that a person is exposed to each day. Typically, melatonin levels start to rise in the mid-to-late evening, after the sun has set. They stay elevated for most of the night. Then, they drop in the early morning as the sun rises, causing us to awaken.

2: Specifically, the report said: “As blue light, above a certain intensity and irradiation time, represents a risk to the retina of the eye, the lamps have to meet the limit value for blue light exposure. This limit value is attained after a longer or shorter irradiation time depending on the intensity of the blue light component. Commercial LED lamps represent no health risk when used correctly. This is also true for vulnerable population groups, such as children or persons, who have very clear, synthetic eye lenses or none at all.”