Really depends where you live, but I suspect for most of the globe that is true(though not necessarily for most of the population). In that case, just open the

Really depends where you live, but I suspect for most of the globe that is true(though not necessarily for most of the population). In that case, just open the windows! Or use a heat exchanger if the temp isn't reasonable outside. But, I was imagining a house sealed up with perfectly clean air and then "dirty" outside air getting in