PHOTO: Xenon lights. (Tim Dillon, USA TODAY) Bright lights, big controversy By James R. Healey, USA TODAY You're driving at night, 'round a bend and  ouch!  you're staring down the barrel of high-caliber headlights boring right at you. Some creep left on the high beams, you grumble. But no, those are too bright, too white, almost blue, like an iceberg. What the heck are those lights? Can that much glare be legal? Isn't it unsafe? The lights are xenon-gas-ignited, high-intensity-discharge (HID) headlights, often known simply (and incorrectly) as xenon (ZEE-non) headlights. They are wildly popular with some motorists, and, if properly aimed, they are quite legal. Read more Video Xenon lights illuminate safety concerns But they are not benign: The glare they produce is real, and its effects measurable in scientific studies. HID headlights pour out more illumination than conventional tungsten-halogen headlights do, especially to the sides. And they do it at the blue end of the color spectrum where the eye's sensitive at night. The result: Oncoming drivers are often surprised by the light and frequently say it hurts. "They're too bright," says motorist Michelle Massey of St. Louis, who often drives her sport-utility vehicle on secondary roads at night. She's afraid that the glare's bad enough, and the vehicles close enough to each other on winding two-lane roads, that a collision is likely. Tim Dillon, USA TODAY The government is looking at the lights. Federal safety regulators are concerned, as well. In fact, the National Highway Traffic Safety Administration (NHTSA) is about to start a process that paves the way for the biggest change in headlight regulations since they were established in 1968. The agency also will look at glare from high-mounted truck and van headlights, and from auxiliary fog and driving lights. NHTSA "has been receiving complaints of glare" and wants to hear, officially, what people have to say, says Richard Van Iderstine, chief of the agency's visibility and injury-prevention division. NHTSA could do nothing, could swing the other way and overhaul regulations so that every headlight would have to be redesigned, or come to rest between those extremes. No decision is likely for more than a year. Seeking input The National Highway Traffic Safety Administration plans to ask for public comment on headlight glare this summer. The invitation will be published in the Federal Register and on the agency's Web site, www.nhtsa.dot.gov. In what could be an epic battle, the xenon warrior princes will be automakers and driving enthusiasts in support of bright whites vs. many ordinary motorists tired of squinting and squirming. "They are major cool," says Gordon Wangers, driving enthusiast and boss at AMCI, a California testing firm that validates automakers' advertising claims. "I never tire of switching them on and watching that bluish-white, fire-up-and-focus routine. In fact, I always do it two or three times to show off if I have passengers," Wangers says. The only drawback Wangers sees is that "on dark, twisting roads, the line between lighted and dark is too pronounced. ... Conventional headlights have a more natural fade area." Wangers says he's not bothered by HID glare when he's on the other end of the beam. Nor is Matthew Strahan of Mount Pleasant, Tenn., who's about to buy an Acura CL with HID lights and thinks "they are useful. They do well in the rain." Driving toward HID lights has "never bothered me at all," he says, and "it makes no difference to me" that others dislike the glare. If it weren't the headlights, people would find something else to complain about, he's sure. 'They bother my eyes' Headlight repair costs soar If nothing else, high-intensity-discharge (HID) headlights have sent headlight repair and replacement costs through the sunroof. The cost trend was sharply upward even before HID lights because automakers had begun using sleek, one-piece composite halogen headlights that integrated with modern styling better than older, less-expensive round or rectangular lights. The composite's one-piece design means it has to be replaced completely even if damage is minor or cosmetic. Add HID lights' expensive components to a fender-bender and stand back. Somebody's going to have to write an enormous check. If it's your insurance company, expect it to eventually show up in your rates. State Farm Insurance, the biggest auto insurer, offers some illuminating contrasts between the replacement costs for standard halogen lights in composite housings and xenon-fired HID lights. As a benchmark for what's dirt-cheap among today's headlights, consider the base-level Chevrolet Astro cargo van. Its headlights are $50 each to replace. Step up to a fancier Astro with composite halogen headlights and the bill rises to $128 - still chump change in the world of HID lights. On the other side are motorists like Rebecca Boudreau of Aliso Viejo, Calif., who sums the universal objection nicely: "I don't like them. They bother my eyes. I think that they're bad for (others who are) driving." What'll make this tough to resolve is that both sides are right: HID lights provide better lighting, and they also produce more glare. Headlights have to meet federal minimum and maximum illumination standards, measured at a variety of points around the light beam. But within those standards, there's enough room  physically and legally  for light to shine where oncoming drivers think it shouldn't. Despite complaints from oncoming drivers, the glare from HID lights doesn't seem to cause accidents, hard as that might be to swallow. NHTSA knows of no injuries or deaths caused by HID glare. And University of Michigan studies of HID glare found that, while it annoys oncoming drivers, it doesn't disable them. "Discomfort glare is not always related to disability glare. Our result is about discomfort," says Michael Flannagan, research scientist at the university's Transportation Research Institute. The university has spent at least 10 years trying to quantify the problem, and thinks it has done so. The short version: Oncoming drivers are bothered by HID glare because of its harsher, blue light. Light from conventional tungsten-halogen headlights is toward the softer, red end of the spectrum. Halogens have to put out 1.5 times as much light as HID lights do to cause the same wincing, squinting and looking away. "We think there is some problem with glare, but we think it's a good trade-off," Flannagan says. "Our overall opinion of HIDs is that they are good things. HID lamps can be, and normally are, better for seeing." A recent Society of Automotive Engineers technical paper agrees. It notes that HID lights' wider beam and greater output makes them dramatically better than tungsten-halogen lights "in detecting edge-of-roadway hazards, such as pedestrians and animals." But the same factors also "may produce more glare," acknowledge the authors, John Van Derlofske, John Bullough and Claudia Hunter of the lighting research center at Rensselaer Polytechnic Institute in Troy, N.Y. 'They're pretty cool' Though HID lights are distracting, toning them down seems unlikely. Automakers are pushing them as the hot item, starting with luxury cars. "They're pretty cool," says Fred Heiler, spokesman for DaimlerChrysler's Mercedes-Benz brand. HID headlights are standard on the top-end Mercedes-Benz S-class sedans and CL coupes, and optional on all other Mercedes models. "There's been some discussion about them because they're brighter, but we know it's primarily the color of the light, and not the intensity, that takes some people by surprise. ... We're going to the trouble and expense in order to use something as close to daylight as possible," Heiler says. Automakers like HID lights because:  They can be profitable, either as stand-alone options or as part of high-dollar packages. Mercedes charges $850 for the HID option, and that's cheap. Catalog firms get up to $1,500 for kits that replace ordinary lights with bona fide HID lamps.  Their efficiency  nearly three times the light from the same power  gives auto designers freedom. They can sculpt and squeeze and shape headlights as they do sheet metal, confident that HID bulbs throw off enough light to meet federal standards. Normal halogen bulbs confined and shaped the same way might not. In other words, HID technology gives designers lots of light to waste in pursuit of styling goals. Because HID lights are on high-end cars, they've become a fashion statement. Auto-parts firms sell blue-tint halogen lights that resemble the HID color, for those dying to have their $9,000 Kia Rios mistaken at night for $120,000 Mercedes-Benz S-classes. "People will put blue filtering on filament bulbs and advertise it as giving 'HID-like performance.' It doesn't. It gives you the coloring," Flannagan says. In fact, ersatz HIDs could be triggering many of the complaints because "They are causing a lot of glare. They're bad optically and scattering light all over," he says. Xenon acts as a fire starter High-intensity-discharge (HID) headlights would take a few minutes to get bright if xenon were not added to the gas sealed inside the headlights. That's how the lights have come to be known, incorrectly, as xenon headlights even though xenon isn't what produces the characteristic blue-white color. Xenon, which ignites easier and faster than other HID gases, acts as a starter. It accelerates HID lights' start-up process, making the technology suitable for cars and trucks, where waiting a few minutes for lighting is impractical. With xenon involved, HID lights are shining pretty well after 1 second, and are as ready as they'll ever be in a few seconds. Xenon is responsible for the bright flash as the headlights are turned on, and it's xenon that glows brightly temporarily until the harder-to-ignite gases are fully awake. Mirrors inside the light assembly capture, amplify and direct the light; lenses aim and focus it. But the real ones have won the hearts of driving enthusiasts. "From a driver's standpoint, they're the greatest thing since sliced bread. The drivers who have them aren't complaining about them. They light up the road markings much better," says David Van Sickle, director of auto and consumer information for the motorists' organization AAA. But Massey, the St. Louis SUV driver, insists there's no need for the special lights: "Regular ones are fine. No matter how much better you can see, it can't be so much better that it's worth blinding people." Road signs play role You can blame U.S. road-sign regulations for some of the HID glare. U.S. signs aren't universally lighted and don't all reflect light the same. Thus, headlights have to throw some light upward and outward, to make sure you can read overhead and roadside signs, according to federal regulations. In Europe, home of most of the world's 2 million HID-lighted vehicles, glare seldom is mentioned. European road signs routinely and consistently are lighted, so headlights needn't beam up and, in fact, are required not to. That keeps the light out of other drivers' eyes. Folks who've been around auto and regulatory circles awhile suspect that complaints are at least partly a reaction to the fact that HID lights are different. NHTSA veterans say the agency got similar ban-the-bulb complaints in the 1980s, as automakers shifted to halogen lamps from their predecessors, sealed-beam lights with bulbs. Halogens appeared brilliant white  blinding, people insisted  in contrast to the yellowish-light sealed beams. Now, halogens are the ones that look yellowish in contrast to blazing, blue-white HID lights. Another Society of Automotive Engineers paper tackles headlight glare and its side issues, warning that "agitation over the effect of glare caused by powerful headlamps has gradually increased until we are threatened with drastic legislation." That one's by engineer Alden L. McMurtry  published in 1917, addressing the transition to electric headlights from acetylene-arc lamps. Contributing: Steven Komarow in Berlin