Outdoor lighting, health and neighbours

The town is reviewing its policy of outdoor lighting to reduce waste and improve its effectiveness.

A few weeks ago I gave a presentation to members of the Planning and Environment Committee about outdoor lighting and they suggested it would be helpful if I submitted an article on the topic to the Chronicle Guide EMC to help inform the public on some aspects of outdoor lighting.

Outdoor lighting serves an aesthetic and a practical purpose and both affect our quality of life.

But you don't get something for nothing. As with any technical advancement, they can also cause unsuspected problems.

The aesthetics of outdoor lighting is somewhat controversial. One person's art is another's eyesore.

Municipal bylaws attempt to define a compromise. This usually means that outdoor lighting should not shine across a neighbour's property. The light fixtures should be shielded and not so bright that scattered light causes glare along streets and into windows.

In fact, a number of European countries have strict limits on the use of outdoor lighting.

On the practical side, product development throughout the 20th century has been minimizing the costs, and maximizing the light output and area of coverage. However, new scientific knowledge can take a decade or more to make its way onto the education system - for it to become 'common sense'.

It is generally believed that light is good because it makes dark places safer, and brightly lit cities look beautiful. Indeed light has become synonymous with urban prosperity.

But there can be too much of a good thing.

What was not popularly known in the 20th century was the link between light at night and our body's reduced ability to overcome disease, infection, stress - in fact most things that we value as our quality of life.

These are not recent findings, they have been accumulating over the last century but this data has been re-interpreted by the science of scotobiology (the biological need for darkness). This new interpretation reinforces the "common sense" that all life forms have evolved to take advantage of their local environment.

More than half the animals take advantage of the anonymity of darkness at night to avoid predation as they forage for food. Both plants and animals subconsciously interpret the lengthening night-time darkness as a cue for the coming of winter, and they begin to prepare by storing food, accumulating fat, or migrating.

For us, when it gets dark, as determined by the fading daytime blue light, our bodies release hormones to initiate and carry out tissue repair, and fight infection and disease.

But blue is a main component in artificial white light that is emitted by new outdoor light fixtures, television and computer screens. We also use white compact florescent bulbs and LED night-lights.

What is not printed on the boxes of white-light bulbs is that the American Medical Association and the World Health Organization have concluded that white light at night poses health risks and contributes to the formation of cancers.

These findings do not undermine the aesthetic and safety benefits of appropriately shielded lighting, but it does suggest that we should use light much more sparingly that we have in the past.