It’s great that we continue to make our home more energy efficient but the more we do the bigger the need is to ventilate your home. There is a happy medium between ventilation and a draft tight home.
Tight homes trap moisture which is not a contaminate but if the humidity is too high (which can happen in tight homes in cold climates) it can lead to condensation which causes mold and fungi growth. VOC’s from building material also get trapped in the home when the home is unable to breath. The most common VOC’s comes from engineered wood products, oil base paints and synthetic carpets.
Plus the usual collection of dust mites, smoke from candles, cooking and shedding from the family pet. A drafty home is not the answer. The simplest ventilation system for a home maybe just upgrading your bathroom exhaust fan or as complicated as installing a multi room exhaust fan.