Many scientists have identified links between air pollution in various forms, including from forest fire smoke, and an increased risk and prevalence of adverse health effects, including brain disorders. Wildfire smoke is a mixture of countless noxious chemical compounds. Fires burning across the warming planet – from California to Greece and Australia – are adding dangerous particulate matter to the atmosphere that includes neurotoxic heavy metals such as mercury, lead, cadmium and manganese nanoparticles. These toxins are an added environmental burden on top of the pollutants emitted by factories, power plants, trucks, automobiles and other sources.

The greatest potential for health problems comes from minuscule particles, smaller than 2.5 microns – or PM 2.5 (for context, the width of a human hair is typically 50 to 70 microns). In the brain they may inflame the microglial cells, the brain’s defensive cells, causing harm to neurons instead of protecting them. Studies show that these extremely tiny particles may damage neurons or brain cells by promoting inflammation. Brain inflammation can lead to conditions like dementia and Parkinson’s disease, a movement disorder in adults.

Though it’s commonly called algae, blue-green algae is actually a type of bacteria called cyanobacteria. These toxic microorganisms thrive and proliferate in warm waterways when excessive nutrients, particularly phosphorus from fertilizer runoff, pour into fresh and brackish water. It produces cyanotoxins. One of these cyanotoxins, β-methylamino-L-alanine, or BMAA, is linked to neurodegenerative disorders including amyotrophic lateral sclerosis, or ALS, Parkinson’s disease and Alzheimer’s disease. Mold toxins, particularly ochratoxin A, can trigger inflammation that may harm neurons and brain function. It has been specifically implicated in Parkinson’s disease.

The U.S. Environmental Protection Agency is currently reevaluating air quality standards for particulate matter. A new EPA inspector general report calls for a strategic plan to control harmful algal blooms.