The Land Transport Authority's (LTA) plan to convert the high pressure sodium vapour street lamps to light emitting diodes (LED) is commendable ("LTA installing smarter, energy-saving street lights"; Jan 4).

It is cost-effective and will also help to reduce Singapore's carbon footprint.

However, a health advisory by the American Medical Association, released on June 14 last year, warns against the indiscriminate use of LED street lighting.

LED street lamps worsen light pollution, as they are brighter with high amounts of blue light. They also increase glare, a danger for driving at night.

Brighter nighttime lighting suppresses the production of melatonin, a substance secreted by the pineal gland in the brain which balances hormones and regulates the body clock.

Brighter lighting at night is also associated with reduced sleep quality and duration, lethargy, impaired daytime functioning and obesity.

White LED street lighting disrupts the circadian rhythms of not only humans, but plants and animals too.

It disturbs many species, even single-celled organisms, that prefer a dark environment. It also confuses nocturnal species' hunting and eating habits, and disrupts the growth patterns of trees.

It is extremely important to preserve Singapore's precious and fragile ecology.

There are ways to minimise the harmful human and environmental effects of LED lighting.

Lamps should have colour temperatures not exceeding 3000K. Moreover, using full cutoff lamps instead of curved glass lamps aids in reducing glare and light pollution.

It is hoped that together with the planned change, the LTA will use lamps of appropriate design and colour temperature to minimise LED lighting's detrimental effects.

Sharne Sulaiman