More than 1 million people in the United States have been diagnosed with Parkinson’s disease (PD), and more than 10 million people worldwide live with the condition. The World Health Organization reports that neurodegenerative diseases like PD are on the rise, yet there hasn’t been a single definitive answer as to what causes it.

Although up to 15 percent of Parkinson’s cases can be attributed to genetics, the remaining occurrences remain a mystery. Scientists believe that environmental factors may play a role, as recent research has uncovered a possible link to air pollution as one potential risk factor for PD.

What Is Air Pollution?

Air pollution is the presence of harmful gases, liquids, and solids that are in the air we breathe. The United States Environmental Protection Agency has identified six main air pollutants that require regulation because of their negative impact on human health and the environment: carbon monoxide, lead, nitrogen oxides, ground-level ozone, particulate matter (PM), and sulfur oxides. Of these six, nitrogen dioxide and PM have generated the most interest from scientists.

Outdoor Air Pollution

Outdoor air pollution, also called ambient air pollution, primarily comes from motor vehicles, industrial facilities, and power plant emissions. Other sources of these pollutants come from natural environmental factors like smoke from forest fires, windblown dust, mold, and spores.

Indoor Air Pollution

Unhealthy chemicals, solids, or other compounds that are in the air within homes or buildings can create indoor air pollution. Combustion sources such as oil, gas, coal, and wood contribute to poor air quality, as do tobacco, building materials and furnishings, cleaning products, and outdoor sources like pesticides. A lack of good ventilation can strengthen the concentration of these particles, resulting in an increased risk of air pollution exposure.

Does Air Pollution Contribute to Parkinson’s?

Many people with PD are interested in investigating possible links between air pollution and the development of PD, and several researchers have been looking into it.

During one 2021 cohort study (a study that follows participants for a long time), researchers reviewed the health data of more than 78,000 individuals in Seoul, South Korea, over eight years. They found a statistically significant association between one particular air pollutant, nitrogen dioxide, and a higher risk of PD. Nitrogen dioxide is one of the pollutants created by trucks, cars, and other vehicles.

Previous studies have shown a link between the incidence of PD and proximity to major roads and highways. Scientists have also noted that developing countries with increasingly poor air quality seem to have rising rates of neurological diagnoses such as PD.

Researchers have also pointed to a possible relationship between the size of the particulate matter and neurological disorders like PD and Alzheimer’s disease. PM that is categorized as fine particles (equal to or smaller than 2.5 microns across or 30 times smaller than the width of the average human hair) could potentially increase the development of PD. PM that is considered coarse (measuring 10 microns or less across) also appeared to play a significant role in the development of PD. These tiny, unhealthy particles are easily inhaled and can travel throughout your body, causing inflammation and oxidative stress.

Scientists Are Continuing to Research

PD has been classified as the fastest-growing neurological disorder worldwide. From 1999 to 2015, the number of people affected by PD more than doubled, from 2.5 million to 6.1 million. This number is projected to double again to more than 12 million by 2040.

Several factors make it difficult for scientists to zero in on what is causing the increase in the disease. Air pollution is everywhere, making it almost impossible to compare exposed individuals to those who haven’t been exposed, no matter if it was short-term or long-term exposure. Because PD can take a long time between the onset and the beginning of symptoms, it can be overlooked entirely, making it harder to correlate between the exposure and the diagnosis.

While researchers continue to investigate the effects of air pollution and neuroinflammation, PD experts are advocating for public health policy changes now to create resources for those living with the disease. These solutions include broad, community-wide networks of PD-specific care staff and living facilities to help increase the quality of life, reduce hospital admissions, and manage other PD-associated complexities.

Talk With Others Who Understand

MyParkinsonsTeam is the social network for people with Parkinson’s. On MyParkinsonsTeam, more than 80,000 members come together to ask questions, give advice, and share their stories with others who understand life with PD.

Are you living with Parkinson’s disease and searching for information on its connection to air pollution? Share your experience in the comments below, or start a conversation by posting on your Activities page.