Can viewing the total eclipse be deadly?
Can viewing the total eclipse be deadly?
It's well known that viewing an eclipse without safety glasses can damage your eyes. A new study asks if excitement over the total eclipse has unexpected downsides.
In case you somehow haven’t heard, there will be a solar eclipse on Monday, April 8th, with a total eclipse visible in parts of the U.S. inside the “path of totality.” Solar eclipses are undeniably cool, and the hype only increases when there’s the additional factor of having the path of totality cross the mainland U.S. If that sounds familiar, it should: a similar total solar eclipse occurred in 2017.
The 2017 eclipse was welcomed with much fanfare, with a NASA official stating “Never before will a celestial event be viewed by so many and explored from so many vantage points – from space, from the air, and from the ground.” It seemed like everyone wanted to see the eclipse, including the President of the U.S.—who famously broke rule #1 of solar eclipses by looking directly at it without safety glasses (which he later put on).
Some enthusiasts really wanted to see the total eclipse, which was easy if you lived inside the path of totality (the 2017 gray band spreading across the U.S. in the map below).
Anyone else who wanted to see the total eclipse to fully experience the daytime darkness had to travel to the relatively narrow path of totality.
In a new research study published in JAMA Internal Medicine, physician researchers Donald Redelmeier and John Staples wondered what problems that travel might have caused.
The hazards of eclipse tourism
A joint survey study between NASA and the University of Michigan estimated that about 20.5 million Americans traveled to another city to view the eclipse (though only about 31% of them traveled all the way to the path of totality). Unprecedented traffic jams were seen in areas across the country—especially less populated areas like Wyoming where an acute influx of visitors can easily overwhelm the roads.
In their study, Redelmeier and Staples asked a simple question: did all that extra traffic lead to an increase in fatal car accidents?
Using data from the National Highway Traffic Safety Administration, they took a look at the 3-day period comprising the day before, the day of, and the day after the 2017 solar eclipse (August 20 to 22, 2017), figuring that many people would have to spend at least a day traveling to and from their eclipse viewing location. They then compared this three-day period to two other three-day periods occurring 1 week prior (August 13-15, 2017) and 1 week later (August 27-29, 2017)—a reasonable set of controls that could account for some of the typical fluctuations in car accidents based on the season and the day of the week—for a total of 6 control days. For each car accident, they figured out when it occurred relative to the eclipse (which occurs at different times in different locations as it passes across the country) based on the location of the crash.
What did they find? In the 3-day period surrounding the eclipse, there were 31% more people involved in fatal crashes than in the control periods +/- 1 week of the eclipse. Looking at the timing of fatal accidents in the hours surrounding the eclipse (plot below), accidents tended to occur at similar times of day as during the control periods, but there were more of them. The study authors estimate that these increases surrounding the eclipse are similar in magnitude to the increases seen in travel-heavy periods surrounding Thanksgiving, Memorial Day, and July 4th.
Is there more to this story?
It’s quite clear from this study that the eclipse led to additional traffic fatalities. This is a solid natural experiment, since a solar eclipse is randomly timed when it comes to the risk of traffic fatalities, and there is nothing else that occurred at that time that would explain such stark differences between the eclipse and control weeks.
While this study makes the “what” happened pretty clear, it doesn’t tell us as much about the “why.” Obviously, most of this can be explained simply by more people on the road for more hours and in more congestion, and this will translate to higher numbers of accidents.
There are, however, some other ideas that came to mind when reading this study. If you look carefully at the plot above, you’ll notice that after the eclipse (in orange), traffic fatalities are about as high as they were before the eclipse. But they are relatively higher after the eclipse when compared to the control weeks (in dark blue). We don’t just have to eyeball it though; by the numbers, the increase in fatal accidents compared to control weeks was higher in the time period after the eclipse (49% higher) than it was before the eclipse (21% higher). In other words, the highest risk period for eclipse-related traffic fatalities is after the eclipse has already happened.
We think this could be explained by a few things.
The first, and perhaps most likely explanation is that while people may have headed to their eclipse-viewing destination at different times, once the eclipse was over, many would start heading home at the same time—this assumption is backed up by reports of a “post-eclipse rush” in 2017.
Another explanation could be the influence of drugs and alcohol from eclipse-related celebrations. Even though the study found that overall, eclipse-related fatal accidents were more often reported as having “alcohol not detected” compared to the control weeks, to the extent there were eclipse celebrations involving substances, they might impact the post-eclipse period more than pre-eclipse.
Finally, we wondered if more accidents were occurring after the eclipse compared to before the eclipse because of vision issues. While we imagine that someone who is enthusiastic enough to travel for an eclipse would be aware of the necessary eye safety measures, they may not have been able to acquire protective glasses or may have taken an unprotected look at the sun just before or just after the totality. If eye damage from the sun (known as solar retinopathy—more on this below) is impairing vision in significant ways, we’d expect to see more traffic accidents after the eclipse than before it.
Most likely though, the roles of eclipse-induced solar retinopathy or increases in driving under the influence, if any, are far smaller than the role of the post-eclipse rush.
What does this mean for this year?
The path of totality for Monday’s eclipse is much larger than the previous one, with many more Americans already living in its path, which means fewer people would have to travel to experience the totality. On the flip side, it could be that recent memory from the 2017 eclipse has increased interest in experiencing the total eclipse, spurring more people to travel.
Experts are recommending that those who travel plan to stay a while in their destination and try not to leave immediately to avoid the post-eclipse rush. Eclipse tourists can hopefully find ways to stretch out their trips by exploring new areas (and boosting their local economies) to make the eclipse experience extra special—and a bit safer for everyone on the road.
N.B. on eclipse safety from two doctors who just can’t help themselves
It’s only natural to want to look at the eclipse, but doing so poses a real risk of eye damage in the form of “solar retinopathy,” or burn-like damage to the layer of cells in the back of the eye (the retina) that detect light and send visual signals to the brain.
We all know that you can damage your eyes by staring directly at the sun on a normal day—after all, you can start a fire with sunlight using a magnifying glass, which is not unlike the lens in your eye. But what many don’t realize is that even though the sun is being blocked by the moon during an eclipse, there’s still enough light coming through to cause retinal damage except during the several minutes of totality for people watching from within its path. Staring directly at the non-total eclipse, even for short durations, can lead to solar retinopathy that might affect vision, and for some it will be permanent.
To view the eclipse safely, NASA and the American Astronomical Society require the use of “safe solar viewers” that meet the ISO 12312-2 international standard. They have provided a large list of suppliers that meet this safety standard here: https://eclipse.aas.org/eye-safety/viewers-filters