April 3, 2023 – No one likes to sit in traffic. Now, new research finds that toughing out rush hour may also present significant brain health risks you never knew about.
A study from the University of British Columbia found that just minutes of breathing in diesel pollution can reduce your brain performance over a matter of hours. Specifically, the researchers found that this kind of exposure can alter your brain’s default mode network, or DMN. The DMN is made up of connected brain regions that are partly responsible for memory and thought process. This activity, the researchers found, was lower in people who had been exposed to diesel pollution.
Disruptions to the brain’s functional connectivity have also been linked to depression. The study does show that brain function will return to normal within hours after diesel pollution exposure stops. But it’s not known exactly how much pollution could cause permanent impairment.
On another front, research published by the American Academy of Neurology found that a particle matter called PM2.5, found in traffic pollution, can raise your risk of dementia. PM2.5 is made up of particles of pollution that hang in midair. Out of 91 million people analyzed, 5.5 million developed dementia; those who were diagnosed with the disease had more exposure to traffic than those who did not. The researchers also found that the risk of dementia grew by 3% for every single microgram per cubic meter of PM2.5 a person was exposed to. PM2.5 particles are very small and can be inhaled very deeply into your lungs, moving into your brain via your nose. It’s thought that this is how brain cell death may start, and lead to conditions like Alzheimer’s.
Car exhaust is just one part of traffic that can have a bad effect on your brain. While there’s no way to avoid the potential hazards completely, the good news is that you can learn about ways to lessen your risk and keep your brain healthy on a daily basis.
What Are the Symptoms of Traffic-Related Brain Problems?
Any kind of dizziness or mental confusion that you notice specifically after being in traffic should be brought to the attention of your doctor.
Hearing issues may be a lesser-known, but important, sign of the impact traffic exposure can have on your brain.
“Overexposure to traffic noise can lead to tinnitus,” said Stéphane F. Maison, PhD, an associate professor of otolaryngology/head and neck surgery at Harvard Medical School and principal investigator at Eaton-Peabody Laboratories at Mass General Brigham Massachusetts Eye and Ear in Boston. “This will cause a ringing or buzzing sound in your ear all the time. These symptoms can lead to sleep deprivation, anxiety, and depression.”
A lesser-known reason for problems with mental skills after hearing traffic noise is hyperacusis. This rare disorder makes exposure to sounds like a car engine unbearably loud. You may get hyperacusis after a head injury, because of a virus, or as a result of conditions like migraine.
“Hyperacusis can lead to depression as well,” says Maison. “If you suspect you may have symptoms of either tinnitus or hyperacusis, get a hearing test.”
Can Traffic Noise Cause or Worsen Mental Health Conditions?
Yes, experts say – depending on how much noise you’re exposed to. A team of British and German researchers reported that if you are very sensitive to noise, traffic sounds that truly bother you can lead to different forms of mental illness, if you are at risk. Traffic noise may also worsen previously diagnosed mental health conditions.
But the way this might occur varies, depending on the person affected.
“I don't think there is a particular length of exposure to road traffic noise which is more annoying," said lead study author Stephen Stansfeld, PhD, an emeritus professor of psychiatry at Queen Mary University of London, U.K. “Times of day, for instance; traffic noise in the early morning or late into the night may be more annoying, disturbing time of rest and sleep.”
Another study found that exposure to transportation noise can lead to a 9% chance of severe anxiety; it’s thought this happens because noises like traffic can stimulate stress hormones in some people.
The key to whether these kinds of adverse outcomes can happen appears to be the length of time you’re hearing the traffic. Prolonged commutes – not just a short drive or walk through a congested area – that are continuous appear to be the most impactful.
“Health effects are more likely with longer duration over time, months and years,” Stansfeld said.
How Can I Protect My Brain During My Commute?
”Invest in custom-made earplugs,” suggested Maison. “You can use standard foam earplugs, but they are not comfortable, and so you are less likely to continue to wear them. Custom-made earplugs are very comfortable because they fit inside the exact shape of your ear.”
Custom-made earplugs are also available in different sound-blocking levels, which is important so you can still hear what is happening around you. Never block your hearing while driving.
Other tips include:
- Roll up your windows. It’s the easiest way to avoid breathing in fumes. Also, make sure the air filter in your car is in tip-top shape.
- Don’t blast music in your car too loudly.
- If you’re stuck in a traffic jam for a long time, turn off your engine to keep excess exhaust from entering your car through vents.
- If you walk or bike to work, choose a route as far away from busy traffic areas as possible.
- Avoid sitting near sources of exhaust on public transportation, like a bus.
- Mask up for your commute, just to be on the safe side.