We don’t have to tell you how getting stuck in traffic can be bad for psychological health. We’ve all experienced the aggravation, frustration, and fatigue that can come with bumper-to-bumper traffic! But there is another danger that we don’t often pay attention to: breathing in toxic fumes that could impact our cognitive health.

If you can drive outside of rush-hour periods, here’s why to do so. If traffic is an unavoidable part of your daily commute, or you live close to busy roadways, then consider getting an air purifier to clean up your indoor air.

Traffic: A Major Stressor—and Worse

A 2004 study found that the daily commute was one of the least pleasant ways we spend our time. In the United States, we spend roughly 42 hours a year staring at the unmoving cars around us. Unfortunately, traffic jams go far beyond being an annoying time-waster.

Traffic-induced feelings of unpredictability and helplessness take a toll on our mental well-being. Sitting in traffic is associated with not only a constant release of stress hormones, but also an increase in blood pressure and negative attitudinal shifts. People who live in “areas with greater vehicular burden” (i.e. more traffic) report having the most depressive symptoms and the lowest health status, according to the National Institutes of Health.

Additionally, the idling vehicles themselves are problematic. Traffic fuel waste is estimated at around $100 billion a year. But perhaps the real problem is all of the toxic fumes that are being released while we sit and wait.

Vehicles are some of the highest sources of air pollutants like carbon monoxide, carbon dioxide, hydrocarbons, volatile organic compounds (VOCs), and particulate matter. When exposed to them in our cars or homes, we’re also exposed to their health risks.

Traffic-Related Air Pollution (TRAP)

Through the process of fossil fuel combustion, most motor vehicles produce dangerous emissions. As a result of slow or idling vehicles, studies investigating rush hour traffic find higher average levels of particulate matter (PM10 and PM2.5), nitrogen dioxide, and ozone—amongst other pollutants.


This is referred to as traffic-related air pollution, or TRAP. It’s quite a fitting acronym since we certainly feel like we can’t escape the smoke and fumes on our daily commutes!


TRAP is known to be a significant risk factor for hypertension and cardiovascular disease. There’s also evidence that TRAP can negatively influence pregnancy outcomes and child development. For young children especially, there has been a link between TRAP and respiratory symptoms like dry coughing, wheezing, bronchitic symptoms, bronchitis, asthma, runny nose, allergic rhinitis, and decreased lung function.


In fact, our long waits on the I-5 can come with a range of adverse health effects for individuals of all ages. These include, but aren’t limited to:


  • Asthma (and exacerbation of symptoms)
  • Reduced lung function
  • Myocardial infarction
  • Worsening atherosclerosis symptoms
  • Dementia
  • Childhood leukemia
  • Adverse birth outcomes
  • Cardiovascular disease
  • Premature death


Overall, roughly 800,000 global deaths annually are attributed to air pollution from vehicles. But there’s another aspect of health that is also impacted by traffic: cognition.

Traffic Pollution and Cognition

Recent studies have demonstrated that TRAP can also have an adverse impact on the central nervous system, leading to oxidative stress, neuroinflammation, and altered neurobehavioral function. In studies conducted with students, older men, and the general public, it’s been found that exposure to traffic-related pollution results in lower scores on cognitive tests.


Particulate matter has been shown to compromise semantic fluency and working memory, meaning that exposure to TRAP can hinder one’s capacity to provide words associated with a certain category (eg., “fruits”) within a short time period.


Black carbon and nitrogen dioxide have been associated with diminished language skills and ability to perform executive functions. Executive functions are the mental processes that enable thinking, planning, self-monitoring, time management, working memory, self-control, and organization.


Even at low levels of exposure, significantly reduced cognitive performance was reported. And even short-term exposure to the pollution from gridlock traffic can impede mental performance.


According to research by Columbia University, elevated exposure to PM2.5 over just 28 days is associated with decreased scores on the Global Cognitive Function and Mini-Mental State Examination scales (cognitive screening tools used to detect cognitive impairment). It was the first investigation of its kind to recognize that even short-term exposure to air pollution can have adverse cognitive impacts.


Age-related cognitive decline and dementia are already problematic around the world. The number of cases are expected to rise—in part due to the neurotoxic effects of air pollution.

Living Near Highways and Air Pollution

Even if we’re not stuck behind brake lights, we may be impacted by TRAP.


Many of these health complications also apply to those who live near major roadways. According to the American Lung Association, around 30-45% of urban dwellers in North America live “next to a busy road”—putting them at risk for asthma attacks, impaired lung function, cardiovascular diseases, and premature death. Those most affected live in a band within 0.2 to 0.3 miles from the highway.


According to Harvard University research, older buildings may also increase risk of traffic-related air pollution. This is especially the case for homes that don’t have central air conditioning and rely on open windows for cooling. In the local study assessing the Boston area, dangerous levels of fine particulate matter (PM2.5) were found in businesses, homes, and schools near highways.

What to Do About Transportation-Related Emissions?

In states like California, there’s actually a requirement to situate all homes, daycares, and schools at least 500-feet away from highways. But air pollution can travel. Wind patterns and temperatures can help TRAP travel away from its source. During the night and in the early morning, pollution can drift up to a mile.


For these reasons, it’s recommended to:


  • Live at least 1,000 feet away from busy road ways
  • Avoid living near roads carrying more than 100,000 vehicles a day
  • Postpone outdoor exercise to mid-morning or afternoon, to avoid the pre-sunrise spike in pollution
  • Keep windows closed until the sun has been up for a few hours can help to keep traffic-produced particulate matter, hydrocarbons, and nitric oxide out of the home
  • Use the ‘recirculate’ button on your car’s ventilation system so that you’re not bringing  air pollution into your car
  • Keep away (if possible) from highway interchanges, freeway ramps, major intersections, and stoplights
  • Avoid the ‘diesel death zone,’ or roads and freeways frequented by diesel trucks


In fact, if you’ve got a newer car, you might already have some protection against TRAP.


While cars just have ionizer air filters that remove some pollen, smoke and dust particles, other car manufacturers have incorporated HEPA filters into their models. These high-efficiency particulate air (HEPA) filters remove 99.97% of dust, mold, bacteria, and airborne particles as small as 0.3 microns (including some particulate matter).


Fortunately, cleaning the air in our houses can also play a big role in improving our health.


Especially for those of us who live close to busy roadways, major intersections, or stoplights, air filters can effectively reduce air pollution. A 2021 study assessed exactly this, finding that using air purifiers indoors near busy roads can limit exposure to ultrafine and other particulate pollutants. This can subsequently result in improvements to blood pressure and other health measures.

Cleaner Air for Better Cognitive Health

While we can’t always control traffic (if only!), we can take steps to ensure cleaner air inside of our homes. Our indoor air can be even more polluted than what’s outside, making it even more important to clean it up. With three units to suit all spaces and families, AirDoctor is here to provide some very essential air purification and the peace of mind that comes with it—even after sitting in traffic.


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