Ventilation allows your home to breath—ridding the indoors of stale, moisture-laden air and bringing in fresh outdoor air. It flushes out potential pollutants caused by combustion appliances or off-gassing materials. Proper ventilation is critical not only to human health but also to the health of the structure, as it controls indoor humidity levels. Humidity, generated by cooking, showering, and breathing, can build up to damaging levels, infiltrate the walls and roof, and cause problems like mold and rot. On the other hand, adequate humidity is essential for respiratory health. Tight homes, which are common in Alaska, require some type of mechanical ventilation, either through fans, range hoods, or a heat recovery ventilator (HRV).