So you use a device that allows the outgoing stale air to pass close enough to the incoming fresh air that the warmer air gives up some of its heat to the cooler air. (energyvanguard.com)
The dry, stale air indoors in winter time is a major culprit for breathing problems. (get-your-baby-to-sleep.com)
«That way you're not breathing in the same old stale air,» he says. (health.com)