People in Southern California with relatively high exposures to wildfire smoke over a decade also had significantly higher risks for dementia, a new study warns.

Wildfire smoke is no longer a one-off event,” said Joan Casey, an environmental epidemiologist. “This is about the health of all Americans.”

Exposure to the tiny pollutants emitted by wildfires may be increasing the older adult population’s odds of dementia diagnosis, a new study has found. Among more than 1.2 million people tracked

That risk will continue to rise as climate change warms the atmosphere and deepens wildfire seasons, said lead author Joan Casey, an environmental epidemiologist at the University of Washington.

In parts of the western United States, wildfire smoke is responsible for as much as half of all particulate matter pollution.