Question

which of the following is true about negative - pressure systems?
they filter out airborne particles.
they force air out through windows, doors, and other openings.
they can bring in airborne particles, such as dust or smoke.
they are more energy - effective than positive pressure systems.

Explanation:

Negative - pressure systems create a lower - pressure environment inside a space compared to the outside. This causes air to flow into the space from the outside through cracks, doors, windows, etc. As air enters, it can bring in airborne particles like dust or smoke. They do not filter out airborne particles (they may even draw in more). They do not force air out through windows, doors, and other openings (that's what positive - pressure systems do). And they are not more energy - effective than positive - pressure systems.

Answer:

They can bring in airborne particles, such as dust or smoke.