Smoke contains microscopic particles known as PM 2.5 because the PM (particulate matter) measures 2.5 microns or less — small enough to easily wiggle its way into our lungs and then into our bloodstreams. Researchers have already connected the particulate matter in wildfire smoke to a higher risk of strokes, heart disease, respiratory disease, lung cancer and other serious conditions.

A new study finds wildfires are burning more high-elevation areas and dramatically impacting the West’s snowpack as a result.

A poor berry crop is driving black bears into Missoula. A hot summer might be to blame.

Once nonexistent in northwest Alaska, beavers are both benefiting from and changing a warming tundra.