Definition of Parkinson’s disease

(© Feng Yu -

SEOUL, South Korea — Living on a busy road could trigger Parkinson’s disease, according to new research. People exposed to dirty air are around 1.5 times more prone to the devastating condition, the study shows.

Corresponding author Professor Sun Ju Chung of the University of Ulsan College of Medicine in Seoul calls for a “targeted public health policy” in response to the findings.

“These findings suggest regulation of air pollutants might reduce the incidence,” says Chung, per South West News Service.

The study could shed light on the rising number of Parkinson’s disease cases across the world. According to the Parkinson’s Foundation, about 1 million people in the U.S. currently suffer from the condition. Doctors diagnose 60,000 Americans with the disease each year. Last year, a study of 63 million Americans found air pollution was linked to a deterioration in health conditions, including Parkinson’s and Alzheimer’s disease.

In this latest study, researchers say toxic particles can travel through the bloodstream into the brain, causing inflammation and oxidative stress. Specifically, the phenomenon was linked to nitrogen dioxide (NO2) emitted by vehicles and industry. The greenhouse gas, produced through the combustion of fossil fuels, is 300 times more potent than carbon dioxide.

“The development of Parkinson’s may be promoted by exposure to air pollution,” says Chung. His team tracked almost 80,000 people over 40 in the South Korean capital for almost a decade. Five-year average district levels of smog were calculated for each residential address.

They found that those whose homes were in the top, rather than bottom, quarter were 41 percent more likely to develop the neurological disorder. The results stood after demographic factors, socioeconomic status and other illnesses were taken into account.

“In this large cohort study, a statistically significant association between NO2 exposure and Parkinson’s risk was identified, “says Chung. “This finding suggests the role of air pollutants in Parkinson’s development, advocating for the need to implement a targeted public health policy.”

‘Significant association’ between Parkinson’s, air pollution

During the study, 338 of the men and women with newly diagnosed Parkinson’s were identified.

“Air pollution is a significant public health hazard. More than 80 percent of urban area residents are exposed to levels that exceed limits set by the World Health Organization,” adds Chung. “Recently, it has been identified to be associated with neuro-degenerative diseases through systemic inflammation, oxidative stress and direct invasion into the brain.”

Parkinson’s is the second most prevalent, after Alzheimer’s disease. It affects more than six million people worldwide. A popular theory is it begins in the olfactory bulb — the part of the brain that controls smell — and the gut, then spreads through the central nervous system.

“Therefore, exposures to environmental pollutants, such as pesticides, metals, as well as air pollution — and the microbiome — have been suggested as risk factors,” says Chung.

In experiments on mice, exposure to ambient toxic particles were found to damage neurons that make dopamine, a hallmark of Parkinson’s. The chemical kicks off movement in the body. Reduction leads to the classic symptoms of tremor, slowness and stiff muscles.

“In conclusion, we identified a statistically significant association between the risk of Parkinson’s and exposure to NO2 for the previous five years, especially at high exposure levels,” says Chung.

The study in Jama Neurology could shed light on increasing numbers of cases.

SWNS writer Mark Waghorn contributed to this report.

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