It’s been in the 70s this week in Washington, D.C., which has been lovely (though snow is predicted for Saturday). This has allowed me to turn off the heat and open the windows for the first time in months. I love sleeping with the window open, even if only for these flukey few days. All this good weather got me thinking about fresh air. The following is from a 1913 texbook called General Hygiene.
Need of Ventilation — Exchanging the impure air of a room for air which is pure and fresh is called ventilation. A small room will require complete change of air within an hour if only one person is in it. A large room will require a complete change of air within a few minutes if many persons are in it. A schoolroom, church, or other meeting place needs to be ventilated all the time that it is in use, for the air will become unwholesome within a few moments, unless a stream of fresh air is constantly flowing into it.
How to Ventilate — Some air will pass in and out of a room through cracks in its doors, windows, floor, and walls. Well-built houses have few cracks, and only a little fresh air will enter them, unless openings are made to the outdoor air. One way of ventilating a room is to open a window. This is often the only way to get fresh air into a room. It is easy to ventilate a room that is heated. Warm air is lighter than cold air, and will rise to the ceiling, like a cork on water. When the upper sash of a window is lowered, a stream of foul air passes out above it. Fresh air enters the room between the two sashes, and through cracks in the other parts of the room. If foul air passes out of the room, we may be sure that other air enters the room. When the lower sash of a window is raised, foul air sometimes passes out through the opening, and sometimes fresh air blows into the room through the opening, but whether the foul air blows out, or fresh air blows in, the air of the room becomes changed.
Wow, I never knew that opening a window was so complex. Wait — there’s more!
Ventilating Bedrooms — Some persons think that a bedroom does not need to be ventilated during the night if it is aired well during the daytime. A person sleeping in a small, closed bedroom will cause the room of fresh air to become foul within an hour after he goes to bed. He will then breathe foul air through all the rest of the night, unless he ventilates the room. Many suppose that a person will not be harmed by breathing air which he himself has made foul. Impure air is as poisonous to the person who makes it foul as it is to another person who may breathe it.
I probably shouldn’t have posted this right before heading to bed!