The Los Angeles wildfires have claimed the lives of at least 24 people and have burned well over more than 12,000 structures.
While the focus is understandably on avoiding the flames, another immediate danger lurks across the county and beyond, one more difficult to escape: smoke.
The most dangerous component of wildfire smoke is fine particle pollution, also known as PM2.5 or soot.
These tiny particles, smaller than one 20th the width of a human hair, can, if inhaled, become embedded in the bloodstream and lungs.
It is estimated that about one-third of all particulate matter pollution in the US now comes from wildfire smoke.