tech: Cell phone urban myth unraveled
Angela Pang, The California Aggie (U. California-Davis)

Along with the ever-increasing popularity of the cellular phone, there also exists uncertainty about its supposed dangers.

The chance that cell phones can set off fires at gasoline stations is not likely. In rare circumstances, though, a static discharge can create a spark that could ignite gasoline vapours.

The stigma about cell phones is further perpetuated by an e-mail currently circulating the Internet that warns about the dangers of their use at gas stations.

When filling up a gas tank, the e-mail alleges, an individual suffered severe burns to the face when fumes ignited as they answered a call while refueling. In another incident, a cell phone placed on a vehicle's trunk rang and inadvertently caused a fire that destroyed both the car and the gasoline pump.

Furthermore, the e-mail states that the Shell Oil company issued a warning in response to the incidents acknowledging that mobile phones can ignite fuel vapours or fires when used near a gas pump.

Shell media relations adviser Karyn Leonardi-Cattolica denies such allegations.

American Petroleum Institute spokesperson Susan Hahn also said that the e-mail claim warning about cell phone use at gas pumps is false.

"As far as the American Petroleum Institute is aware, cell phones have not caused a fire during refueling," Hahn said. "We think it very unlikely that [cell phones] could."

Nevertheless, Leonardi-Cattolica said Shell is adopting precautionary approaches and recommends that people do not use their cell phones while at the pump. She said that Shell is making this recommendation because they cannot verify whether or not a cell phone might not be the cause of fuel ignition incidents at gas stations.

But, assistant professor Frank Osterloh from the University of California-Davis chemistry department said that cell phones are "very safe" to use while at gas stations.

"Cell phones operate on low voltage and thus cannot produce an electrical spark sufficient to ignite gasoline vapour," he said.

In addition, Osterloh said cell phones are designed to transmit and receive radio waves of very low power which are "extremely unlikely" to set gasoline vapours on fire.

Because cell phone manufacturers include warnings about the equipment, Hahn said that some API member companies began posting cautionary signs against cell phone use at their respective service stations.

Though cell phones may not cause fires, motorists must be aware that they are not completely safe at the gas station. According to Hahn, a static discharge can generate an electrical spark at the gas pump and possibly ignite gasoline vapour. She said, however, that this type of incident is rare.

She added that static electricity may discharge and ignite the vapours, combined with oxygen, that collect around the fuel nozzle during refueling.

In fact, static electricity - which is the imbalance of positive and negative electron charges - has been found to be the cause of several fires. According to statistics on the Petroleum Equipment Institute's Web site, there were 12 reported static related fires in 2003, and 31 in 2002, in the United States.

"Cell phones are not related to static electricity, and the best way to avoid a static-induced incident is to stay at the pump during the average two minutes it takes to refuel," Hahn said.

According to Osterloh, people are at much greater risk in causing an electrical spark through what is known as the triboelectric effect. This occurs when two different insulators, like skin and the polyester in a car seat, rub against each other, allowing electrons to flow from the skin into the polyester. A static electrical charge is thus created by the insulators and not from using a cell phone, Osterloh explained. Upon touching a conductive surface, such as a metal, the charge is released in the form of a spark, which could potentially ignite gasoline vapours.

Static electricity usually requires dry conditions, and, therefore, is more of a problem in the winter because cold air is usually less humid.

He suggested that one can reduce the risk of uncontrolled electrical discharges by touching another metal surface before handling sensitive equipment such as a fuel nozzle. Touching the metal would discharge the person and prevent further electrical sparks that could ignite the gasoline.

Even if a spark were to occur, Osterloh notes that people should not be too worried, because modern gas station nozzles are designed to absorb gasoline vapours.

Though it is unlikely that cell phones could cause fires, as the e-mail suggests, motorists should still be cautious at the gas pump.

"Consumers should not do things like talk on the phone during refueling, because safe fuel handling requires your full attention," Hahn said.

U-Wire

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