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.

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 over a decade in Southern California,

Now, in an 11-year study of more than 1.2 million Kaiser Permanente members in Southern California ages 60 and up, a group of doctors from around the country said that rates of dementia rose significantly among residents who had been frequently exposed to wildfire smoke over a three-year-long period.

As Baby Boomers hit retirement, about 1 in 6 Americans is now over the age of 65. The number of Americans living with dementia is projected to skyrocket—but the proportion of older Americans who develop dementia has actually decreased.