My parents always tell me if I should keep my door partially open as in "closed" but not locked into the frame.

However, my door has a line of space under it which would technically allow some degree of air flow.

My room is small, so dust accumulates pretty quickly. Would having the door open cause more dust to accumulate or less?

Does it really matter if I close my door or not for air flow when I sleep/am in it during the day? How much of a difference does it really make if the door is only partially open?

I’m asking this because I want to keep my door fully closed to reduce the amount of noise from outside my small room, but am wondering if it's worth doing so with airflow, dust accumulation, temperature, and O2/CO2 levels.

  • If that door is the only way for air to get in(no windows/vents) then you probably want it open more, but is okay to close it to keep out noise when you are in it. Dust does not care much.
    – crip659
    Nov 27, 2021 at 22:27
  • Thanks, I only have air coming into my room from my vent, where my door crack is the only thing letting air out. Would it make a big difference if I left it partially open vs closed in terms of CO2 levels if there's no air intake unit?
    – ShangWang
    Nov 28, 2021 at 0:14
  • @crip659 If there are no windows, then (at least in many jurisdictions in the US) it is not legally a bedroom.
    – Glen Yates
    Dec 29, 2021 at 0:25
  • I live in an apartment, there's windows you just can't really open them.
    – ShangWang
    Dec 29, 2021 at 15:28
  • You don't indicate the size of the room, but even a small, tightly sealed (i.e. no HVAC supplying air in, no gap under the door) 10x10' bedroom would take quite a while for one person (at normal respiration rates) to lower the O2 level or raise the CO2 level enough for it to be a problem.
    – FreeMan
    Jan 28, 2022 at 18:03

2 Answers 2


Unless you live next to a building site, sawmill etc then most of the dust comes from your dry skin and clothes.

Ventilation is one thing and controlled is good, cleaning is another.


The most important reason to keep a door open is for air flow if you have a forced air HVAC system (with no individual return in the room itself). Closing the door can cause increased back pressure on the supply side resulting in excess stress on the blower motor.

However, if you have at least a 1/2" gap* between the bottom of the door and the floor, then that should allow adequate air flow even with the door closed.

*This assumes 1 standard 10"x4" supply register in the room, if you have a particularly large bedroom with more than 1 register, then you will need a correspondingly larger gap.

  • Thanks! It seems air only goes in, not out. Despite that the door crack should suffice I guess.
    – ShangWang
    Dec 29, 2021 at 15:28

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