Formaldehyde in a dream signifies a sense of fear, anticipating the worst. It is often used to represent death or decay.
If you have dreams about decay, this could also be a sign that something is not right in your life, and that you need to think more about your relationships and health.
In a dream, formaldehyde usually signifies that someone close to you has died. It can also represent if you are preserving something or trying to keep something alive. Formaldehyde in a dream can also mean that you are depressed or are feeling like you are on death row.