The Bay Area Air District has issued an air quality advisory in the region for Tuesday because of smoke from a wildfire in Central California.

Researchers found that wildfire smoke can raise ozone to dangerous levels, posing hidden health risks even in remote areas.

Air quality has taken a serious hit across the United States as a two-fold blow of wildfires in the West and in Canada have sent smoke pouring across large sections of the country — a problem that’s set to linger for days.