More than 50,000 people have died prematurely in California over a decade due to exposure to toxic particles in wildfire smoke, according to a new study.

Wildfires create smoke containing PM2.5, tiny particles roughly one-thirtieth of a human hair that can embed themselves deep in the lungs and enter the bloodstream. The particles have been linked to numerous health conditions and premature death. Previous research has found that the wildfire smoke is exposing millions of people in the US to the harmful pollutant.

In a study published in Science Advances this week, researchers used a new epidemiological model to examine the impacts of wildfire PM2.5 exposure between 2008-2018: a period that includes some of the state’s most destructive and deadly fire seasons. There were at least 52,480 premature deaths attributed to exposure to the inhalable particulate matter from wildfires.