Schools will send an email to parents/guardians on a weekly basis documenting each day during the previous week that the CO2 concentration in any school cafeteria exceeded 1,100 ppm for more than 30 minutes. Emails will not be sent if the CO2 concentration remains below 1,100 ppm.

High-efficiency particulate air (HEPA) filtration units do not increase the indoor air carbon dioxide (CO2) concentration. HEPA filtration units remove particulates from the air but do not remove CO2, which is a gas. Only outdoor air ventilation lowers the CO2 concentration in the indoor air. 
 

Elevated CO2 concentration does not typically present a hazard in a school system setting.  In an occupational setting, the Occupational Safety and Health Administration’s (OSHA) Permissible Exposure Limit (PEL) for CO2 is 5,000 ppm. This 5,000 ppm threshold is far above the 2,000 ppm CO2 concentration that is considered to be an indicator of poor ventilation and well above the levels found in HCPSS cafeterias that rarely exceed the 1,100 ppm target.

The rate at which CO2 is generated within an indoor space is proportional to the number of occupants in the space. If outdoor air ventilation is not provided at a rate of 15 cfm/person, an elevated CO2 concentration above 1,100 ppm can result.

It is important to note that carbon dioxide (CO2) is a gas that is generated by humans when they exhale. It is not to be confused with carbon monoxide (CO).
 

Generally, a CO2 concentration above 1,100 ppm for more than 30 minutes would be considered an elevated concentration; however, it only means that outdoor air ventilation is being provided at a rate that is less than 15 cfm/person as recommended by the American Society of Heating, Refrigerating, and Air-Conditioning Engineers (ASHRAE). In an occupational setting, the Occupational Safety and Health Administration’s (OSHA) Permissible Exposure Limit (PEL) for CO2 is 5,000 ppm.

The concentration of carbon dioxide (CO2) in an indoor space provides a good indicator of how effectively outdoor air ventilation is being provided. Since cafeterias have the largest concentration of students and staff in school buildings, they provide the highest natural levels of CO2 and serve as a good measure of the effectiveness of outdoor air ventilation as an additional COVID-19 mitigation strategy.

General health and safety resources and information can be found online at www.hcpss.org/health. 

Community groups, including but not limited to PTAs and boosters, that use HCPSS facilities after school hours will not be required to provide vaccination status or undergo testing. These activities are voluntary and not associated with HCPSS activities. The universal masking requirement will remain in place for all facility users.

Because they are voluntary, school sponsored events that occur before and after school and are approved by school administrators may occur with visitors without a vaccine or testing requirement. School administrators will take efforts to ensure other applicable mitigation efforts are implemented. The universal masking requirement will remain in place for all participants.