Fowler Associates Labs

Crocs Fashion Clogs Possible Cause of Static Electricity in Swedish Hospital
(See our evaluation below article : Maybe it is just a crock)
April 30, 2007

Hospital spokesman said employees that wear crocs footwear could turn into "a cloud of lightning" because of static electricity.

The following article was paraphrased from several news reprt: Blekinge hospital in southern Sweden is banning its employees from wearing a popular footwear, known as crocs. The hospital believes that the slip-on plastic clogs generate static electricity that can cause medical equipment to malfunction.

Hospital spokesman Bjorn Lofqvist said that the shoes are blamed for at least three incidents in which respirators and other machines failed to perform properly. No injuries have been reported. Lofqvist went on to say that hospital staff wearing the clogs could turn into "a cloud of lightning" because of the static electricity.

The colorful plastic shoes are composed entirely of a patented, closed-cell resin material that softens and molds to the feet with body heat and have become extremely popular in the past few years. They are made by Crocs, Inc., an American company based in Niwot, Colorado.

"Its been a problem for many years, but now there are so many people that have them," Lofqvist said. Hospital officials haven't decided whether to ban the shoes throughout the hospital or just in certain areas.

It should be noted that a Swedish hospital in the town of Ornskoldsvik has not experienced any problems with the Crocs because the floors there are antistatic, hospital spokeswoman Erika Jakobsson said.

Testing at the ESD Journal's Static Labs revealed our Croc shoes were not that bad. Using the ESD Association's STM 97.1 and STM 97.2, we found the resistance of the shoes to ground were 1E12 Ohms or 1 Tera Ohm. While walking on clean non ESD protective vinyl floors, we found less than 500 Volts generated. This is one test on one pair of shoes at 12 % RH.

We would welcome other labs to let us know their results. Maybe the Swedish hospitals have other problems? Maybe the story is just a crock about the Crocs.

Seriously, the resistance shows that a person could accumulate charges over a short time but the propensity to charge in our tests is fairly low. The closed cell material used in the Crocs may have chemicals which disallow too much charging. We look forward to comments from readers.