LJUBLJANA, Slovenia - Driving past a supermarket, Andrej Mohar is pleasantly surprised. The lights have been switched off overnight.
“I am enjoying the economic crisis because they don't have money for illumination,” he said.
Three years ago, Slovenia became the first country in the world to introduce a national law to crack down on light polluters.
It is still the only one.
Supporters of the move now say other countries should follow suit.
Stargazers like Mohar, a spokesman for Dark Sky Slovenia, an organization that lobbies Slovenian businesses and individuals to abide by the law, are not the only ones who stand to benefit. It is, supporters say, the route to enormous energy savings, safer roads, reduced cancer risks and healthier insect and bird populations.
“Tell me the reading,” the 48-year-old activist said, pointing to what looks like a Star Trek phaser at a perfectly ordinary looking gas station across the road. The readout said “4.6,” comfortably within the permitted brightness limit. The same measurement for an innocuous-looking sign standing outside a car repair workshop comes in at over 500, around a hundred times the legal level. Such is the fallibility of the human eye in judging right from wrong.
Dark Sky Slovenia has told the owner of the rogue signage that the contravention could mean a fine of 12,000 euros ($15,300), but to no avail. Dark Sky Slovenia is not in the business of disciplining lighting outlaws, Mohar said, “We have never painted a light black.” He added: There are simply too many billboard owners for the authorities to effectively enforce the law.
Instead the organization concentrates on notifying those flouting the rules and offering them advice on how to comply. Since the law started to be phased in the official inspectors say they have made 100 on site inspections, issued 36 orders to comply and imposed 10 penalties. The message has begun to get through.
On a hill overlooking the city stands a small church, lit up at night like many others in this part of Europe. This one, however, has been lit with the law in mind. Each of the two lamps mounted on poles in the ground has a reverse silhouette of the outline of the church in front of it to prevent light overshooting its roof, sides or tower. This, despite in an exemption for historic buildings like this one from the laws prohibiting uplighting.
Billboards, street lights and other public lighting, however, is illegal if it emits light above a horizontal angle. At a shallow angle, stray light can travel over 125 miles. In practice, this means billboards have to be lit from the top and that street lights need to be shielded by a flat piece of glass.
Any kind of dome tends to scatter light up, particularly when it becomes dirty. So far 40 percent of Ljubljana's 34,000 street lamps have been replaced. In these places, there is no bright daisy chain of lights of the typical night cityscape, just a lit strip of road and there is noticeably less glare from above as you drive along one.
One of the reasons the law gained acceptance, Mohar said, is that the environment minister at the time the law was proposed, conservative Janez Podobnik, was a doctor.
Even in small amounts, bluer light is also associated with preventing sleeping people from producing melatonin, an antioxidant said to guard against breast, prostate and colon cancer.
“He knew the function of melatonin,” Mohar said of Podobnik. Driving through a flood-lit truck stop, he added: “They will be tired in the morning."
Partly for this reason, the law favors the yellow light produced by high-pressure sodium elements over the new generation of white LED lighting. Such elements are also substantially cheaper to install and consume the same amount of power.
The color of the light is important in understanding the impact of light pollution, explained Gregory Vertacnik, a physicist working for Dark Sky Slovenia.
(Courtesy of Dark Sky Slovenia)
Light towards the shorter-wavelength blue end of the spectrum, present in larger amounts in LED lighting, scatters more, creating a brighter halo in the night sky.
It is also this section of the spectrum that most efficiently turns off melatonin production, even through closed eyelids, and attracts moths, bats and birds to spend their time in fruitless circling.
“Those who promote white light always argue that it makes it possible to distinguish colors in the dark,” Mohar said. "But why do you want to distinguish colors in the dark?”
One concession to white light is made on pedestrian crossings, with the lighting industry arguing that older people whose eyes tend to be less good at picking up yellow light find it easier to see hazards.
The organization representing the lighting industry, the Slovenian Lighting Society, is also skeptical about the broader effectiveness of the light pollution laws.
Spokesman Matej Kobav said the authority in charge of policing light pollution simply excuses the inaction of billboard owners and other businesses, citing more serious pollution problems.
"It is very difficult because we are over-occupied with other tasks," confirmed Tatjana Bernik of the Environmental Inspectorate, the agency in charge of enforcing the law. The reason billboards so often go unpunished is technical, she said, "Usually they use LED diodes and it is difficult to find out if they are in compliance or not."Kobav, however, said he accepted the arguments in favor of lighting restrictions, adding that they were a boon for the lighting industry: replacing the street lights in Ljubljana alone would bring in 1 million euros, with upgrades in smaller towns and villages bringing in about 50,000 euros.
He said the zero-degree-rule was too strict, however. Fewer lights would be needed if light were allowed to escape one or two degrees above the horizontal. Such a relaxation would significantly reduce installation and energy costs.
There are signs that Kobav's arguments are gaining ground. The government this month relaxed the laws governing floodlights on football stadiums, allowing them to give off light at five degrees above the horizontal. Kobav hopes further concessions will be offered before full compliance is required in 2016.
Besides, he said: “Restricting light emissions to zero degrees makes it is almost impossible to create a nice view of Ljubljana.”