Replacing the standard warm-white top quality halogen light, commonly used for headlights, with other light sources is in my opinion not a good idea.
Since their introduction in early 1990’s, more and more cars have been equipped with high intensity discharge Xenon Arc lamps. They’re about twice as bright as halogen headlights or more, and are said to improve visibility for the driver. But what few seem to have considered is how irritating they can be for meeting traffic:
– They’re blueish (around 4100K), which creates more confusion and distraction in an otherwise even traffic stream. Lights from meeting cars are not supposed to attract your attention by sticking out. And blue light is not good for the eyes.
– An especially irritating feature is that they flicker and quickly shift shade from blue-white to purple-white and back as the car drives past, instead of giving a calm, even light like halogen does. This can be very distracting for meeting traffic.
– They’re very bright and glaring. That’s not good for for road safety. Being blinded and distracted in crucial traffic situations is not exactly helpful.
The Swedish Road Administration say they keep getting complaints from other drivers but can’t do anything about it since these lamps tend to get approved by EU as car manufacturers apply. A condition for this approval is that they must be precisely adjusted so as to avoid glare for others, but this is obviously not always done, or is easily maladjusted again depending on packing weight etc.
– Getting a xenon-lit car driving behind can be even worse than briefly meeting one, especially if it’s a van or SUV where the headlights come up higher. Having the inside of one’s car lit up like a stadium does not make for safe driving.
If you’re considering switching to xenon, please be mindful of other drivers and consider staying with traditional halogen if possible. If you the car is already equipped with xenon, please make sure lights are well adjusted at all times.
Also beware of Faux Xenon, e.g. Osram’s Cool Blue – “the designer lamp”– a product that shouldn’t exist. Putting a blue filter on a standard halogen bulb is about the stupidest thing you can do. These should definitely be banned, as they are both energy inefficient and dangerous!
Nowadays, headlights in general are also much brighter than they used to be – manufacturers constantly boast about how much more light their product will give you:
* Osram Silverstar “Thanks to their special technology SILVERSTAR lamps illuminate the road with an up to 50% brighter light in the crucial zone 50 to 75 m in front of the vehicle than a standard lamp”
…and in the crucial vision zone of meeting traffic, pedestrians and bicyclists.
* Philips X-treme Power “Philips X-treme Power bulbs deliver up to an astounding 80% more light than standard halogens”
…right into the unsuspecting eye of everyone but the driver.
If the European Commission ever wanted to do anything truly useful, why not ban xenon lights as a safety hazard, faux xenon as a waste and hazard both, and set firm limits to how bright headlights can be?
Update 1: Now LED lamps have been introduced for car headlights. Very bright white light that at least doesn’t flicker and shift like xenon light, but it is still chillingly cool-white and quite glaring. For some reason, many SUVs are equipped with LEDs – which is an extra bad idea since the light is even more glaring coming from that hight.
However, using red and amber LED lamps as stop- and signal lights in the back of the car is a great idea! Producing coloured light while using practically no energy, is what diodes do best.
Update 2: SCENIHR, the Scientific Committee on Emerging and Newly Identified Health Risks, in its amended report 2011, page 72, actually mentions glare from meeting traffic as a real hazard for night drivers:
“Glare from bright head lights may induce accident”
http://ec.europa.eu/health/scientific_committees/emerging/docs/scenihr_o_033.pdf
Update 3: YouTube video where the glaring property of LED headlights can be seen quite clearly:
http://www.youtube.com/watch?v=IaGqA8BItDk&feature=related
Great article about the history of headlights:
History of Automotive Headlamps – From Acetylene to LEDs
And an informative comparison between halogen, xenon and LED:
Battle of the Headlights: Halogen vs. Xenon vs. LED
Greenwashing Lamps 