Indoor exposures to air pollutants are associated with a significant burden of disease. In EU-27 the burden is estimated to be over 2 million healthy life years annually. This report investigates how this burden can be mitigated and in particular presents health based estimates for ventilation, including discussion of necessary control strategies for indoor sources and filtration needs for polluted outdoor air. The report allows for construction engineers, health professionals and legislators to weight the benefits of various strategies for optimal control of the health risks. Energy efficiency impacts are also shortly covered.