Light pollution: the easiest pollution to tackle

One Change: Light pollution can lead to eye issues and can affect our melatonin levels

Of all the forms of pollution that beset us, light pollution might be the easiest to tackle. Night-time illumination from Ireland nearly doubled in the two decades to 2014, such that 95 per cent of the country now has night skies that appear brighter towards the horizon due to electric lighting, according to Prof Brian Espey of the School of Physics at TCD. This matters from an energy perspective, but also for wildlife and our mental wellbeing.

Many mammals, birds, reptiles and insects are naturally photoperiodic. Their behaviour and physiology depend on the circadian rhythms, such that growth, development, reproduction, eating and locomotion can be effected by artificial light. And plants, too, depend on nocturnal and diurnal influences which can be affected by light pollution, leading to physiological changes and increased opportunities for insects, birds and mammals to predate on them.

The glare and spillover from night-time light also impacts us humans, as we’ve evolved over millennia to be in synch with natural light patterns. Interfering with this can lead to eye strain, loss of clear vision and premature aging of the eyes. It can even affect our melatonin levels, which in turn can cause sleep disorders, headaches, stress, increased anxiety and some forms of obesity.


The solutions are straight forward. First, is to adjust our exterior home lighting. Security lights are often 10-20 times more powerful than is necessary, which wastes money and risks creating dark shadows in the illuminated areas, which just increases the danger. 150w or 600 lumens, is more than sufficient in most cases. Unshielded bulkhead lighting should be avoided, since the majority of the light actually shines into people’s eyes, causing glare, which can actually make an area less visible, while causing severe light pollution in the environment.

Choose LED lights for reduced energy consumption but make sure they are warm colour tones, such as “warm-white” (less than 2,700 Kelvins). Install a motion sensor so that light is on only when needed. Angle the light downwards to ensure it only illuminates your property and does not trespass on your neighbour.

Once our home lighting has been adjusted, we need to turn our attentions to our local authorities, and to educating them about the importance of maintaining existing dark areas and the negative impact of blue-rich LED lighting on ecology and on human health. Ask them to consider dimming or switching off lights between midnight and 5am in certain areas, and to ensure their own public buildings and car parks do not create light pollution or light trespass. Louvers can now easily be fitted to street lighting to ensure the lights fall only on the road and pavement.

Not only will these steps lead to ecological and psychological improvements, but the energy and carbon savings will be significant. Currently, the town of Newport in Co Mayo is set to become Ireland's first beacon of dark-sky-friendly development, thanks to a new plan funded by the Heritage Council. We need to encourage all of our local authorities to follow the lead set by Mayo County Council. For advice and more information visit