The debate taking place throughout California about plastic bags continues to grab headlines. This is especially true in San Mateo County. Incorporated cities are considering joining a county-wide plastic bag ban and now a statewide ban has been proposed for the state.  These bills are based on common misperceptions about bags.

As a retired captain in the National Oceanic and Atmospheric Administration, I’ve followed the environmental side of this debate with deep interest.

A recent letter to the editor (“Good reasons to ban plastic bags,” January 19) in the San Mateo Daily Journal published in response to an op-ed by a local plastic bag manufacturer offers a window into widespread myths about plastic bags.

As an individual with a long career in oceanic and atmospheric science, I’d like to correct the record.

Criticism of plastic bags often focuses on their purported impact on marine environments. I have heard numerous claims in this debate – some which border on the absurd, including that plastic bags make up 10% of beach litter. The truth is plastic bags have very little impact on the oceans. Critics of the bags often depict a swarm of plastic in the Pacific Ocean, sometimes called the “Great Pacific Garbage Patch.”

In an effort to better understand the facts behind this alarming allegation, Oregon State University conducted a study of the Pacific Ocean and not only found that no such “Patch” exists, but also that “if we were to filter the surface area of the ocean equivalent to a football field in waters having the highest concentration (of plastic) ever recorded…the amount of plastic recovered would not even extend to the 1-inch line.”

Bans on plastic bags are simply not effective in reducing litter. How can they when plastic bags make up less than 0.5 percent of the waste stream? I’m aware that plastic bags have become a popular target for some environmentalists but they are misleading the public and legislators by ignoring or distorting the facts. The truth is that our environmental impact is very complex and major progress will not be made simply by banning one item.

Given how emotionally-charged the rhetoric and imagery of this debate can become, it’s especially important that all parties involved have a solid understanding of the facts. Much of my career was spent researching and protecting our oceans, and their preservation is a priority we all share. Facts—not emotion—should be the basis of this and all environmental debates.

Tim Wright is a retired National Oceanic and Atmospheric Administration (NOAA) Captain. He has a degree in Physical Oceanography from the University of Washington and an Executive MBA from the Washington University Olin School of Business. He holds a USCG license as an Unlimited Chief Mate, 1600 Ton Master on Oceans.