Does she really think the terminus of this state of affairs ends in the suffocation of everyone in the house? If that's what's happening, and you don't live in some sort of special, hermetically-sealed house, then she's incorrect.
The most likely scenario, from what I know, is that your home's attic lets in fresh air through the soffits on the eaves of the roof. That air gets pulled into the home (as well as helping prevent mold, etc., in the attic) in order to give you fresh air. Even with all the windows closed, your house is receiving fresh air. I'm no expert, but people have been making homes with HVAC systems in them for a long time. They figured this stuff out. That's what standards and laws are for.
If your wife just wants the air in the house to be less stale, that's fine, but surely that could be accomplished by opening a bunch of windows periodically and for a small amount of time. She's not the only person in the house; the comfort of others is also very important, and 90F is approaching dangerous heat.
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