Ventilation of the air is necessary due to complacence of human need for air, for dilution of polluted air, amount of fresh air which depends from allowed level of harmful components in room air (polluting component can be , which is produced by human breathing, technological process), for enabling air circulation in a room, which is the one of components for comfort conditions. To satisfy human needs for fresh air, it is necessary new amount of outer air. Relevant moment in determination of needed amount of fresh air is calculation of dilution of harmful component (for example, and human breath) or appeared in technological process. Based on such determined amount of fresh air we can approach to a choice of system for ventilation and conditioning of certain work recycled or technological rooms or establishments. In that context in paper is shown calculation methodology of air amount for ventilation of static and variable sources of appearance harmful components in work and manufacturing rooms.