What HVAC measures have been taken to provide maximum air filtration and ventilation in school buildings?

In accordance with the recommendations of the American Society of Heating, Refrigerating, and Air-Conditioning Engineers (ASHRAE) and the Centers for Disease Control and Prevention (CDC), the decision was made by the HCPSS Division of Operations in May 2020 to provide MERV 13 air filters in HVAC units wherever possible and to maximize outdoor air ventilation by verifying proper operation of outdoor air dampers, airside economizers, and exhaust fans. 

HCPSS does not recommend opening windows or exterior doors specifically in buildings due to the potential this could create for elevated relative humidity and subsequent humidity mold. Additionally, there is the potential for drafts resulting in an inability to maintain the design space heating and cooling setpoints and the introduction of pests and allergens. Outdoor air ventilation for all classrooms is provided through the HVAC systems. Opening windows or exterior doors also presents security concerns.
Air Filter Replacements
Between July 8, 2020 and September 4, 2020, the HVAC Shop in Building Maintenance replaced 12,439 air filters in the HVAC units serving all HCPSS buildings. In some cases, HVAC units are equipped with two air filter tracks, one for a prefilter and one for a final filter. In these cases, MERV 8 air filters were installed in the prefilter position and MERV 13 air filters were installed in the final filter position. If there was only one air filter track in the airstream (i.e., there was no prefilter), MERV 13 air filters were installed.
Verification of Outdoor Air Damper and Airside Economizer Operation
During summer and fall 2020, HCPSS Operations staff and outside contractors checked the operation of outdoor air dampers and airside economizers for over 900 HVAC units in all HCPSS buildings. Deficiencies were identified and addressed at the time if they were minor; otherwise, deficiencies were noted for follow-up work, which was completed in January 2021.
Verification of Exhaust Fan Operation
HCPSS Operations staff checked the operation of over 900 exhaust fans in all HCPSS buildings during summer and fall 2020. Minor deficiencies were identified and immediately addressed; other deficiencies were noted for follow-up work, which was completed in fall 2020.