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Comment by ubertoop | Hacker News Reader

> Ventilation: indoor pollution is usually many multiples of outdoor. You want a an MVHR (or MEV) system to exchange the air in the house for fresh air with low heat (energy) loss.

Can you expand on this? What is polluting the indoors? How can I verify it's true at my home?

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Your body constantly sheds skin flakes (dust).

Tiny mites find those flakes, cover them in enzymes that break down skin, then wait for them to break down enough to eat.

When a puff of air lifts the dust into your lungs, those digestive enzymes attack your lungs.

Your body produces extra mucus in response, to trap dust on the way in, and inflames the tissue surrounding any damage to prevent infection taking hold. Neither response is pleasant.

And if you think that's bad, just do an air sample after running a vacuum. Micron filters or not. It's one of the many reasons I love my central vacuum system - it exhausts outside my home :)

anything not N₂, O₂, argon, or H₂O is possibly air pollution, though some things are more harmful than others. many mundane things indoors give off VOCs (volatile organic compounds), from couch cushions to stained/painted woodwork. carbon dioxide, carbon monoxide, and ozone are air pollutants too. then you've got particulates like soot, smog, dust, pet dander, fly ash, dust mites, mold spores, pollen, etc. and then anything that smells from candles, perfumes, and soaps to smoke from cooking is more pollution. and that's just the stuff in the air (much more of a risk to humans than airborne viruses btw).

Indoor air pollution is mostly carbon dioxide, combustion byproducts (in houses with propane/gas cooking appliances), volatile organic compounds that offgas from plastics, paints, rubbers, and similar materials, and assorted particulate matter.

To answer the second half of your question, you can pick up one of these to measure CO2 level (1). Some specific things to check would be the kitchen while cooking, or the bedroom overnight.

If you live in a moderate climate, rather than an HEV, you can likely get away with just running bathroom exhaust fans for a portion of the day; you can get switches that will do this automatically.

1: https://www.amazon.com/Hydrofarm-Autopilot-Desktop-Monitor-L...

Cooking in the kitchen is one of the worst offenders for air quality, for example.

Smoking cigs beats it on a PM 25 and PM 10 readings.

... how are you supposed to not cook in your kitchen?

I suppose I should just eat all my food delivery now?

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