A study in the journal Science reports that forest fires release large amounts of long-lived soil pollutants, including mercury (Hg), polycyclic aromatic hydrocarbons (PAHs), and perfluorinated substances (PFASs), into the air and environment[5][7]. After a fire outbreak, these pollutants can enter the atmosphere and subsequently be deposited in the landscape or washed by rain into waterways and groundwater[5][7]. Analyses show that elevated concentrations of contaminants in water and sediments can persist for several years after a wildfire; a large study monitored 100,000 water samples from 500 watersheds and found that some water quality parameters remained elevated for up to eight years[6]. Fires alter soil chemistry (e.g., pH, organic matter, and redox conditions), which can increase heavy metal mobility and bioavailability[2][6]. The concentration of harmful forms of some elements (e.g., conversion of chromium to a more toxic form) depends on the temperatures reached during the fire and local soil conditions[1]. Released contaminants can enter the food chain or drinking water sources through runoff, erosion, and infiltration into groundwater[3][4][5]. In the article, the authors emphasize the need to test soils and waters after a fire because ash and burned soil layers contain higher concentrations of heavy metals and organic contaminants than unburned soil[4][5].