Ash is highly acidic and prone to dispersing through the air when it is disturbed, which can be as easy as breathing on it. When swept up into the air, the building’s climate control system will pick it up and blanket entire rooms, making it much more difficult to get rid of. Because it is acidic, it will eat away at a number of materials if it sits for long, especially glass, metal and drywall.

Within a couple days, ash can permanently etch glass, including windows, weakening them considerably and forcing replacement. During this time, any drywall covered in ash can permanently discolor, turning to a sickly yellow and becoming a major eyesore. After a couple weeks, ash will corrode metals, which can result in water leaks or other expensive problems.

And ash is not just a risk to the building. It can also irritate lungs, throats and eyes, resulting in breathing difficulty, coughing, sneezing and general discomfort. This is particularly troublesome for children with asthma, as the ash can trigger an attack.