Final answer:
Ventilation procedures should begin prior to entry and continue throughout the operation.
Step-by-step explanation:
Ventilation procedures should begin prior to entry and continue throughout the operation. Ventilation is necessary to maintain a safe and healthy environment during certain operations, such as painting, cleaning with chemicals, or using appliances that release pollutants into the indoor air.
According to the information provided, outdoor air can enter and leave a building through infiltration, natural ventilation, and mechanical ventilation. Natural ventilation refers to air movement through opened windows and doors. It is important to start ventilation prior to entry to ensure that any pollutants or contaminants are being effectively removed from the indoor air.
By starting ventilation before entering a space and continuing it throughout the operation, you can help maintain a safe air quality and reduce the risk of exposure to harmful substances.