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May 17, 2021

Bad Air and Parkinson Disease—The Fog May Be Lifting

Author Affiliations
  • 1Center for Health + Technology, Department of Neurology, University of Rochester Medical Center, Rochester, New York
  • 2Norman Fixel Institute for Neurological Diseases, Department of Neurology, University of Florida, Gainesville
  • 3Associate Editor, JAMA Neurology
  • 4Weill Institute for Neurosciences, Department of Neurology, University of California, San Francisco
JAMA Neurol. 2021;78(7):793-795. doi:10.1001/jamaneurol.2021.0863

At the same time James Parkinson was describing 6 individuals in London, England, with a novel shuffling disease, British meteorologist Luke Howard was detailing great fogs clouding the air. While both Parkinson disease and air pollution predate the early 19th century, their prevalence have risen together (Figure1). World regions with the most air pollution (eg, Europe and North America) have generally had the highest rates of Parkinson disease. Those with less pollution (eg, Africa) have had lower rates. Countries undergoing rapid industrialization with poor air quality (eg, China and India) have rising rates of Parkinson disease.2,3 These data are not hard evidence but have led many researchers to investigate a potential link.

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Eliminating the production of NO2 pollution
DAVID KELLER, MD, MS | Internal Medicine
The study by Jo et al [1] concludes:
"We identified a statistically significant association between the risk of PD and exposure to NO2 for the previous 5 years, especially at high exposure levels. We found no evidence for the association between the risk of PD and exposure to [other common urban air pollutants, including] PM2.5, PM10, O3, SO2, or CO."
The authors did not identify the main sources of the atmospheric NO2 pollution to which their subjects were exposed, nor what environmental regulations could be enacted to decrease NO2 exposure.

In the accompanying editorial by Dorsey et
al [2], the editorialists state:
"They [Jo et al] found that exposure to NO2, produced primarily from burning fossil fuels in automobiles and power plants, was associated with a subsequent diagnosis of Parkinson disease."
However, NO2 pollution need not be produced. if clean fossil fuels are employed.
For example, methane (a fossil fuel also known as "natural gas") has the chemical designation CH4, and is composed of one carbon atom attached to 4 hydrogen atoms. The combustion of methane, which is the chemical reaction that generates electricity in gas-turbine power plants, is summarized in the following chemical equation: CH4 + 2O2 ---> CO2 + 2H2O + HEAT. One molecule of methane (CH4) reacts with 2 molecules of oxygen (2O2) to create one molecule of carbon dioxide (CO2) plus two molecules of water (2H2O), plus heat. This heat is used to boil water into steam, which spins a gas turbine, which, in turn, spins an electrical generator. In principle, no NO2 pollution need be produced in this process, if there are no contaminants in the methane.

Gasoline, another widely-used fossil fuel, contains a mixture of alkanes of many lengths, including octane, which is 8 carbons long. The combustion of octane, typical of all alkanes, is as follows: C8H18 + 17O2 ---> 8CO2 + 9H2O + explosive heat energy; the explosive heat energy propels an automobile, without producing NO2, if there are no contaminants in the gasoline. So, in principle, the combustion of an uncontaminated hydrocarbon fuel, such as gasoline or natural gas, can provide electrical power or automobile fuel without producing NO2 pollution.

The major source of urban NO2 pollution turns out to be diesel fuel [2], which is burned in trucks, heavy equipment, some cars, and buses, including school buses. Diesel engine exhaust is thick, black, malodorous smoke, which should be targeted by new regulations to reduce NO2 pollution, in the effort to slow the pandemic of neurological degeneration in the industrial world.

1: JAMA Neurol. 2021;78(7):800-808. doi:10.1001/jamaneurol.2021.1335
2: Five facts about diesel the car industry would rather not tell you.