The only real health protection is Aero Guardian
When advised to stay inside, keep your windows and doors closed. It's OK to keep the air conditioner running, but make sure the filter is clean, and close the fresh-air intake to prevent smoke from entering, according to the CDC.
Health officials in Riverside County warn of toxicities. Ash from burned homes and other items will likely contain potentially toxic materials if breathed in or touched with wet skin, such as metals, chemicals, and potentially asbestos, according to a news release. If you do get ash on your skin, wash it off immediately. Inhaled ash may be irritating to the nose, throat and lungs.