Study: Living Near Dense Traffic Increases Incidence of Dementia

Traffic 2

On Jan. 4, medical journal The Lancet published the results of a Canadian study linking living near major roadways to increasing incidence of dementia.  On the upside, they were also interested in any links with Parkinson’s Disease and Multiple Sclerosis, but found no correlation. The study received assistance from Public Health Ontario (PHO) and the Institute for Clinical Evaluative Sciences (ICES) along with scientists from the University of Toronto, Carleton University, Dalhousie University, Oregon State University, and Health Canada.

The team, led by Dr. Hong Chen, sampled adults living in the province of Ontario between 20-50 years old and those between 55-85 years old beginning in 2001 (6.6 million total). Participants had none of the neurological ailments at the time the study began. Residential location and proximity to major roadways was derived from post code addresses beginning five years prior to the start of the study (1996). Major roadways are defined as tollways, highways, and the like.

As the study progressed, incidences of each disease were verified with provincial health agencies.

The results marry together the data, while excluding unrelated causes (things like diabetes, obesity, smoking, brain injury, and poverty … income is a factor in overall health).

Roadways and Dementia 1

They found that between 2001 and 2012, there was a 7 percent increase in the incidence of dementia for those living within 50 meters (164 feet) of a major roadway when compared to the general population. For those living between 50 to 100 meters (164 to 328 feet) away, the increased incidence was an additional 4 percent, while 101 to 200 meters (328 to 656 feet) away was 2 percent above normal. Beyond 200 meters (656 feet) levels of dementia returned to normal.

For those living in major cities (like Toronto) the incidence of dementia increased 12 percent for those living both less than and greater than 50 meters (164 feet) from a major roadway.

“Our study is the first in Canada to suggest that pollutants from heavy, day-to-day traffic are linked to dementia. We know from previous research that air pollutants can get into the blood stream and lead to inflammation, which is linked with cardiovascular disease and possibly other conditions such as diabetes. This study suggests air pollutants that can get into the brain via the blood stream can lead to neurological problems,” says Dr. Ray Copes, chief of environmental and occupational health at PHO and an author on the paper.

Researchers also suggested that in addition to pollutants from nitrogen oxides, ultra-fine particles from tire wear and the like, long-term exposure to road noise may also be a factor.  The study wasn’t designed to identify what specifically may be the cause, only that proximity increases incidence.

As a high-riser, I wonder if the distance effects from major roadways are also vertical.  Is someone living on a lower floor at greater risk than someone living on the 20th floor? I suppose that depends on whether chemical dissipation is vertical (pollutants rise from the ground) or horizontal (wind blows pollutants away) or both.

Interestingly, in Dallas, I’ve noticed many senior living facilities bordering highways.  Given that they’re typically “sewn-up” fresh air-wise, I’m hoping they have some serious air filtering to protect residents who, through age, are more susceptible to neurological diseases like dementia.

Findings like these should fuel adoption of electric cars and expansion of public transit coverage and options. The goal being to reduce vehicle numbers and improve air quality.

An ounce of prevention is worth a pound of cure. Dementia care is costly, but more importantly, it’s a grizzly way to spend your final years.

Dementia is a broad term for a number of diseases that cause cognitive, memory and behavioral degradation.  Alzheimer’s is the most known and most prevalent, accounting for 70 percent of dementia cases according to the World Health Organization (WHO).   As Baby Boomers age, dementia will similarly boom with expectations that today’s 47.5 million global suffers will balloon to 135.5 million by 2050 according to WHO. Seven to twelve percent of these cases may be caused by vehicle pollution.  A sobering thought.

Location, location, location indeed.

Remember:  High-rises, HOAs and renovation are my beat. But I also appreciate modern and historical architecture balanced against the YIMBY movement.  If you’re interested in hosting a Staff Meeting event, I’m your guy. In 2016, my writing was recognized with Bronze and Silver awards from the National Association of Real Estate Editors.  Have a story to tell or a marriage proposal to make?  Shoot me an email

2 Comment

  • In response to retirement facilities being built in urban settings and close to highways, senior living communities are designed with greater levels of filtration on the air that is supplied for ventilation and cooling/heating. In fact, they have dual levels of filtration, one set of filters on the primary air supply and a second set on the local supply air, similar in nature to a hospital system. It seems doubtful that with these levels of filtration, air pollution inside the facility is of concern.