Santa Ana winds will continue whipping through Southern California through Thursday, sparking fears that progress made fighting wildfires that have scorched over 40,000 acres and left 28 dead could be reversed and more blazes could break out.

On Monday, LA Mayor Karen Bass said that the city was prepared to respond to any new fires, but warned that the Santa Ana winds could kick up ash from previous fires. The airborne ash could not only make the air in some areas toxic, but the high winds could also carry that ash to other communities in Southern California.