Past U.S. Solar Eclipse Saw Rise in Deadly Traffic Crashes

The last total solar eclipse in the U.S. in 2017 was associated with an increased risk of fatal traffic crashes, researchers found.

During a 3-day period around the eclipse on August 21, 2017, there were 10.3 fatal crashes per hour, compared with 7.9 per hour during two control periods, according to Donald Redelmeier, MD, of Sunnybrook Health Sciences Center in Toronto, and John Staples, MD, MPH, of the University of British Columbia in Vancouver.

That translated to a significantly increased relative risk of fatal crashes around the eclipse (RR 1.31, 95% CI 1.15-1.49, P<0.001), and an absolute risk of 1 extra crash fatality every 95 minutes, they reported in a research letter in JAMA Internal Medicine.

“The risks are not due to transient changes in outdoor light,” Redelmeier told MedPage Today. “Instead, they most likely derive from increased amounts of driving.”

The highest risk appeared to come in the few hours after the eclipse ended, Redelmeier said, noting that the highest total number of crashes was from 6 p.m. to 7 p.m. the day of the eclipse, a few hours after it had ended.

“It’s not when everything is dark. It’s when you let your guard down,” he said. “So much of the increase in risk isn’t on the path of totality. It’s not because of the 3 minutes of distraction. It’s the hours around the time and, in particular, the evening hours afterwards.”

The magnitude of the increased risk was similar to that seen around major holidays such as Thanksgiving, Memorial Day, or the Fourth of July weekend, the researchers noted.

In 2017, the path of totality fell within 300 miles of driving distance for a third of all Americans, and an estimated 20 million people traveled to another city to view the eclipse, resulting in substantial traffic.

To assess whether this increased the risk of fatal crashes, Redelmeier and Staples collected data from the National Highway Traffic Safety Administration Fatality Analysis Reporting System. They compared the 3-day exposure interval (August 20-22) with two other 3-day periods: August 13-15 and August 27-29.

Overall, 741 individuals were involved in fatal crashes during the eclipse interval, compared with 1,137 individuals involved in fatal crashes over the 6 control days. Relative risks were consistent across various subgroups, and were “accentuated under clear weather conditions” they wrote, with similar results seen in secondary sensitivity analyses.

The study was limited by a lack of data on travel distances and on individual interest in viewing the eclipse. Still, Redelmeier noted that “almost all of these crashes could have been prevented by a small change in driver behavior,” such as following speed limits, minimizing distractions, wearing a seatbelt, and allowing ample headway.

Neil Bressler, MD, editor-in-chief of JAMA Ophthalmology who recently published a “patient page” in that journal about safe viewing of solar eclipses, warned that the risks around total solar eclipses — including the one coming up on Monday, April 8 — extend beyond traffic crashes.

“The greatest risk for vision is if someone views the sun when the eclipse is partial,” Bressler said. “From a safety perspective for viewing the eclipse, if an individual views the eclipse at any time other than totality, they risk having the sunlight … permanently burn the center of the retina.”

To view the eclipse safely, he recommended using either shade No. 14 welder’s glasses, aluminized Mylar filters, or a pinhole projector.

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