Air pollution and Parkinson's disease

How air pollution, genes, and metabolism combine to shape Parkinson's disease

Air pollution is one of the few risk factors for neurodegeneration that nearly everyone shares and that policy can change. I study how air pollution exposure contributes to Parkinson’s disease (PD), and which biological pathways carry that effect from the air into the brain.

Air pollution and PD

My work draws on the Parkinson’s Environment and Genes (PEG) study in California’s Central Valley, with lifetime residential and workplace address histories. In PEG, long-term exposure to traffic-related air pollution was associated with higher odds of PD. Criteria pollutants such as NO2 and PM2.5 cannot identify which constituents matter, so I also examined specific air toxics and found the most consistent associations for nickel, benzene, and 1,3-butadiene.

Genetic susceptibility

Genetic susceptibility amplified the association. In a meta-analysis of PEG and a Danish study, people with both a high PD polygenic risk score and high exposure had about 3 times the odds of PD compared with people who had neither.

Metabolic pathways

To understand mechanisms, I used untargeted serum metabolomics. Air pollution exposure was associated with altered lipid and amino acid metabolism and lower tyrosine, a precursor of dopamine, pointing to inflammation and mitochondrial dysfunction as plausible pathways.

Metabolic pathways enriched among air pollution-associated serum metabolites in PEG.

A narrative review summarizes research on air pollution and neurodegenerative diseases, including Alzheimer’s disease and related dementias, and the challenges ahead: earlier exposure windows, PM2.5 constituents, and comorbidities such as cardiovascular disease.

Selected references

Kwon D, …, Ritz B. Traffic-related air pollution and Parkinson’s disease in central California. Environmental Research. 2024.

Kwon D, …, Ritz B. Traffic-related air toxics and Parkinson’s disease in California’s Central Valley. Science of The Total Environment. 2026.

Kwon D, …, Ritz B. Interaction between traffic-related air pollution and Parkinson disease polygenic risk score. JAMA Network Open. 2025.

Kwon D, …, Ritz B. Untargeted serum metabolomics and air pollution in Parkinson’s disease. npj Parkinson’s Disease. 2026.

Kwon D, …, Ritz B. Challenges in studying air pollution to neurodegenerative diseases. Environmental Research. 2025.