The Elk Fire near Red Feather Lakes is expected to cause thick smoke in Larimer County on Thursday.

The Larimer County Department of Health and Environment has issued an Air Quality Advisory for Larimer County until 9 a.m. Friday morning.

If smoke is thick or becomes thick in your neighborhood, you may want to consider staying inside, especially if you already suffer from breathing problems or breathing-related health issues. Unhealthy smoke levels are considered to be when visibility is less than five miles in you neighborhood.

The Larimer County Sheriff's Office said the Elk Fire was at 622 acres and 40 percent containment as of Thursday morning — mandatory evacuations were still in place in some spots.

There were 80 firefighters on the ground on Thursday morning with 60 more ordered on the way. Air operations to fight the fire have also resumed.