Another large study has found negative health effects from living close to high-traffic roadways - this time a higher risk of dementia. The closer to the heavy traffic road, the higher the risk - with the highest risk in people living less than 50 meters (164 feet) from a high-traffic roadway, especially in major urban cities.
Other studies suggest that the air pollution from the high-traffic roadways is the problem - that the pollutants from vehicles (such as from the exhaust, and the wear of the tires) get into the body and brain and cause systematic inflammation. (see posts on air pollution and the brain) Traffic-related air pollution includes ultrafine particles, nitrogen oxides, and particles. And the constant noise is stressful. However, this large Canadian study found no association with multiple sclerosis or Parkinson's disease and living close to heavy traffic roadways. (See all posts on air pollution and the brain.) From Science Daily:
People who live close to high-traffic roadways face a higher risk of developing dementia than those who live further away, new research from Public Health Ontario (PHO) and the Institute for Clinical Evaluative Sciences (ICES) has found. Led by PHO and ICES scientists, the study found that people who lived within 50 metres of high-traffic roads had a seven per cent higher likelihood of developing dementia compared to those who lived more than 300 meters away from busy roads.
Published in The Lancet, the researchers examined records of more than 6.5 million Ontario residents aged 20-85 to investigate the correlation between living close to major roads and dementia, Parkinson's disease and multiple sclerosis....The findings indicate that living close to major roads increased the risk of developing dementia, but not Parkinson's disease or multiple sclerosis, two other major neurological disorders.
"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.
People who lived within 50 metres of high-traffic roads had a seven per cent higher likelihood of dementia than those who lived more 300 meters away from busy roads. - The increase in the risk of developing dementia went down to four per cent if people lived 50-100 metres from major traffic, and to two per cent if they lived within 101-200 metres. At over 200 metres, there was no elevated risk of dementia. -There was no correlation between major traffic proximity and Parkinson's disease or multiple sclerosis. [Original study]