Ventilation and air purification recommendations for all types of residential and commercial buildings: In each room, maintain as a minimum the fresh air ventilation standard of 21 cubic feet per minute (cfm) per person as recommended by the World Health Organization (WHO).

This level of fresh air can be conveniently measured, with a modest safety factor, as a carbon dioxide (CO2) reading of 800 parts per million (ppm) or less.

This report introduces COVID-19 ventilation design principles and applies them to school buildings. Please note that following all the recommendations of this report will NOT guarantee complete safety. There is no guaranteed level of safety except for complete quarantine.

Following these recommendations will ensure that existing HVAC systems are performing in accordance with existing best practices. Depending on the system type, the amount of fresh air ventilation may be able to be increased fairly easily, with existing equipment.

There is no single standard in this report for how much fresh air ventilation is needed. More is better, and fresh air is one factor that can be combined and traded off with other COVID-19 safety measures.

In addition to general ventilation, for new COVID-19 patient isolation rooms, and for general health office areas, we have specific ventilation recommendations that apply no matter what the general ventilation levels.