Axios

The U.S. cities with the worst air quality in 2023 — mostly in the Midwest — had particle pollution levels two to three times higher than what the World Health Organization (WHO) recommends, according to a new report.

The big picture: It's not coincidental that the cities with the worst air quality last year were in the Upper Midwest and Mid-Atlantic, as those regions were smothered in smoke from Canada's unprecedented wildfire season.

Middle age is a tipping point for the brain and can offer clues about the risk of cognitive decline and dementia, emerging scientific evidence shows.

Why it matters: The decades between 40 and 60 years old could be a key time for early interventions and provide a knowledge base for new therapies to prevent disease.