The manufacturer of a $100,000, high-tech lightning protection system installed at Ravens' stadium says the devices will prevent the sort of strikes that injured 11 at Robert F. Kennedy Stadium in Washington last weekend, but some researchers say it won't work as advertised and could lull designers into a false sense of safety.
The system, purchased more than a year ago, consists of six devices resembling dinner-plate-sized flying saucers attached to aluminum poles on the stadium's light towers.
Its manufacturer says the system, known as an "early streamer emission" network, will protect everyone from the fans in the upper deck to the quarterback on the field. During electrical storms, each unit emits an ionized field that provides lightning with a more attractive connection than people and buildings, according to the company, Lightning Preventor of America Inc. of Spring-ville, N.Y.
The company says each unit can protect a diameter of more than 600 feet. That's twice as good as conventional lightning rods.
"I know our system will do what we advertise," said Kenneth Heary, president of Lightning Preventor, the manufacturer and supplier of the system.
Others aren't so sure. The National Fire Protection Association, which issues standards for conventional lightning protection devices, has refused to issue a standard for early streamer emission systems, and the Underwriters Laboratories won't certify them. One of the nation's premier lightning experts, Martin Uman, director of the Lightning Research Laboratory at the University of Florida at Gainesville, termed the devices "snake oil."
"The majority of the scientific community do not believe that [the devices] work as advertised," said Uman, author of several books on lightning.
The early streamer emission devices probably work as well as conventional lightning rods, but if designers use fewer of them, assuming a larger protective range, the stadium could be less safe, he said. Heary's literature says the system can save money because the effective zone of each rod is larger and, thus, fewer are needed and they can be spaced wider.
The vulnerability of fans in open-air stadiums to lightning strikes was vividly underscored last Saturday when a bolt of lightning injured 11 people at RFK Stadium attending a concert.
RFK was protected by about 45 grounded lightning rods, said Stanley Maxwell, chief electrician for the stadium. The lightning that injured the concert-goers on Saturday bypassed the rods and struck fans in the first few rows of the lower seating bowl.
That's unusual, but not unheard of, say experts. The lightning probably originated directly over the field and headed straight down.
Stadiums, frequently the tallest buildings in their vicinity, are uniquely vulnerable to lightning-related injuries.
"It's incredible to me that more people don't get killed in them," Uman said. "It's an accident waiting to happen."
The Mid-Atlantic probably sees an average of 15 lighting strikes per square mile each year, he said. Most land harmlessly on trees, buildings or the ground. But when they hit people the results can be disastrous: A lighting bolt packs a punch of 20,000 amps and exceeds 50,000 degrees in temperature. More people are killed by lightning on average each year -- about 8,000 -- than any other weather event, including tornadoes and hurricanes.
"Lightning has got its own agenda. It is extremely capricious," said Richard Kithil, executive director of the National Lightning Safety Institute in Louisville, Colo., an organization independent of equipment manufacturers.
He said there is no fool-proof way to guard against lightning strikes outdoors. He doesn't think that early streamer emissions systems do anything beyond what a conventional lightning rod of similar size would do.
"That's advertising disguised as science," Kithil said. "It's a lot of hype."
The federal National Institute of Standards and Technology, at the request of the National Fire Protection Association, conducted a review of scientific literature on early streamer emission systems a few years ago. It concluded that the theory behind such devices was "plausible," but there wasn't enough evidence to say definitively that the systems do or don't work as claimed.
"There is reason to doubt that it significantly extends the maximum range of protection" beyond that provided by conventional lightning rods, the NIST study concluded.
Loucas G. Christophorou, a physicist with the NIST, said: "I don't think we have the answer yet. The physics that underlies them makes some sense, but it is their preventive value that is open to some question. There are people who argue for them and people who argue against them.
"It is questionable whether they work as advertised," he said.
Heary, president of the firm that supplied the Ravens' system, said that the devices have been used for decades and are thoroughly tested. Standards have been approved for their use in Spain, France and Portugal.
The Intertek Testing Services of Cortland, N.Y., a competitor of the Underwriters Laboratories, has certified the system based on more rigorous testing than conventional lightning rods have been subjected to, Heary said.
Officials with Intertek did not respond to requests for information.
Heary said his firm even guarantees buildings with its units for up to $10 million in damage. He said the company has never had a failure and had to pay.
The company is suing the National Fire Protection Association for its failure to issue standards for the devices, as it does for traditional lightning rods. A proposed standard for early streamer emission systems was defeated by the association when critics disputed the equipment's effectiveness.
"They are entirely wrong," Heary said.
Maryland Stadium Authority project manager Alice Hoffman said: were told it was the best system that money could buy. We were very careful to make sure that every part of the bowl and field was covered."
But Uman, who has had his own records subpoenaed in the Heary suit against the NFPA, said the conventional system of lightning rods "has stood the test of time."
He said the early streamer emission systems tests he has seen were performed in laboratories, a poor substitute for atmospheric testing.
"There isn't any evidence that they work and there's lots of reasons to think they don't," Uman said.
How it works
How an early streamer emission device works:
When an electrically charged thundercloud approaches, it causes an electric field that generates discharge channels in the form of "leaders" that seek out active electrical ground targets.
Objects on the ground, including people, trees and buildings, emit varying degrees of electrical activity in response to the approaching leader. This electrical activity can take the form of an "upward streamer," or electric discharge that serves as a conductive pathway.
When the leader encounters a sufficient streamer, a connection is made. Electricity passes between them in a bright flash of lightning.
A lightning rod is designed to be the preferred conductor by virtue of its placement -- up high -- and its conductive material, which can create a strong streamer.
An early streamer emission device attempts to enhance the effectiveness of the rod by boosting the number of electrically conductive particles in surrounding air.
Theoretically, this electric field will spawn a streamer that will connect with the leader earlier than streamers emitted by nearby objects. Thus the lightning is drawn away.