Dementia: Another Reason to Curb Air Pollution

A new study appears to show that dementia rates increase among people who live near busy traffic, adding to growing calls for world governments to do more to reduce air pollution – not just for the sake of the environment, but for our health too. 

Published this month in “The Lancet,” the study begins by examining past research that suggests a host of neurological conditions including dementia, Parkinson’s disease and multiple sclerosis may increase if we are routinely exposed to high levels of pollution.

To investigate these claims, researchers from Public Health Ontario reviewed data on nearly 6.6 million people in the Canadian province of Ontario between 2001 and 2012. All members of the population sample were free of neurological disease at the start of the analysis. The researchers ascertained where the people lived — and how close to major roadways — by using their residential postal address. They then examined the rate of diagnoses for dementia, Parkinson’s disease and multiple sclerosis by using databases routinely maintained by Canadian provinces.

The researchers found that living near a main road appeared to impact the rate of dementia, but not Parkinson’s disease or multiple sclerosis.

The total number of dementia cases during the life of the study was 243,611. If the researchers analyzed the incidence rates by how close the sample was to a major road, the risk increase became apparent.

If a person lived within 50 meters of a major road, he or she was at a seven percent higher risk of developing dementia. At 50-100 meters, individuals faced a risk four percent higher than the average.  Between 101 and 200 meters, they faced a two percent risk increase.

Even after adjusting for variables like poverty and unhealthy habits, such as smoking, the relationship still held. In total, the researchers believed that between seven and 11 percent of all dementia cases in the 50 meter proximity group could be caused by traffic pollution.

Dr. Hong Chen, a lead researcher in the report, told the BBC:

Increasing population growth and urbanization have placed many people close to heavy traffic, and with widespread exposure to traffic and growing rates of dementia, even a modest effect from near-road exposure could pose a large public health burden.

The study author adds that further research is needed to explore exactly what might be causing this rise. Technically, this research can’t tell us if particulate matter from road traffic, a major risk factor for a number of diseases, is to blame. Traffic noise, as well as other variables, may also play a part.

Researchers also want to understand why there appeared to be no association when it came to Parkinson’s or MS.

There are many potential factors that could have affected the results, but this is certainly cause to consider changes in how we plan our towns and cities.

Rob Howard of University College London told The Guardian:

We know that major road air pollution is bad for general health and this latest study doesn’t tell us whether the small increase in dementia risk is driven by indirect effects or whether proximity to traffic directly influences dementia pathology. Regardless of the route of causation, this study presents one more important reason why we must clean up the air in our cities.

World governments are facing significant pressure to cut emissions as more and more evidence suggests a link between a decline in mental and physical function and higher exposure to pollution.

It isn’t just in the elderly, either. Autism rates appear to be impacted by pollution, while levels of physical diseases in infants, such as respiratory disorders, tend to go up — and sometimes significantly.

City dwellers wishing to cut their risk of exposure have few options. China is among the list of nations currently dealing with a heavy smog problem.

One solution to come out of Beijing has been to invest in green corridors, or park spaces that disperse traffic and allow for cleaner air. While this isn’t necessarily applicable everywhere, health experts have suggested that people living in cities try to use routes away from major roads when they are out walking, and to use parks and greenways whenever practical to cut daily exposure.

Photo Credit: Isengardt/Flickr


Marie W
Marie Wabout a year ago

Thank you for sharing

Nang Hai C
Nang Hai Cabout a year ago


Brett C
Brett Cloudabout a year ago


Brett C
Brett Cloudabout a year ago


Siyus C
Siyus Copetallusabout a year ago

Thank you for sharing.

Leong S
Leong Sabout a year ago

Thank you for sharing

Dagmara W
Dagmara Wabout a year ago


Marija M
Marija Mabout a year ago

tks for sharing

heather g
heather gabout a year ago

Wish all authorities acted on this ......

Leo C
Leo Cabout a year ago

Thank you for posting.