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Possible technology service interruption.

On Friday, September 29, 2023, between 6 and 8 p.m., City Schools will be updating our technology infrastructure. This maintenance may cause intermittent service disruptions to all City Schools' technology services. This includes any systems that require internet access and cloud-based services. Please plan accordingly. 

Expires on 10/1

In-Person Air Quality Plan

City Schools is providing this In-Person Air Quality Plan, which includes the air ventilation plan for in-person learning at City Schools managed buildings. The attached list indicates if the building’s ventilation is addressed by air filter upgrades or air purifiers.

Charter School staff and families: Please contact the school for an update on the status of your school’s plan.

For questions or more information about air quality, please email


The American Society of Heating, Refrigerating, and Air-Conditioning Engineers (ASHRAE) encourages combinations of higher efficiency mechanical filters and HEPA air purifiers to help mitigate infectious aerosol transmission.  

Each building was assessed to certify that it had a functioning mechanical ventilation system that can receive the higher-efficiency MERV 13 filter without adversely impacting system operations. Where this is not possible, room measurements were taken to provide sufficient portable HEPA air purifiers that achieve MERV 13 or better levels of performance. All health suites, wellness rooms, cafeterias and gymnasiums received air purifiers or air scrubbers regardless of the building’s overall ventilation plan.

Building ventilation is only one part of a comprehensive mitigation strategy that includes all five of the Center for Disease Control's (CDC) recommended mitigation strategies for in-person instruction: 

  • Consistent and correct use of masks 
  • Social distancing to the largest extent possible 
  • Hand hygiene and respiratory etiquette 
  • Cleaning and disinfection 
  • Contact tracing in collaboration with the local health department
What is the indoor air quality plan for all City School Buildings (ventilation plan)?

The indoor air quality plan for each school can be found in the Air Quality Plan:

  • 81 schools will receive MERV 13 upgrades
  • 67 schools will receive portable air purifiers (most of these schools have systems that service common and administrative spaces that will receive MERV 13 filter upgrades)


Counts do not include charter/contract schools in their own buildings or non-academic buildings.

What is a mechanical ventilation system?

A system that provides better indoor air quality in homes and commercial buildings by extracting stale air and/or by supplying fresh air. Mechanical ventilation systems may include supply fans, exhaust fans, or a combination of both.

How did you determine the indoor air quality plan for each school building?

Each building was assessed by City Schools Mechanical Services and Building Maintenance staff to certify that it has a functioning mechanical ventilation system that can receive the higher-efficiency MERV 13 filter without adversely impacting system operations. Where this was not possible, ASHRAE (American Society of Heating and Refrigeration Engineers) recommends providing a High-Efficiency Particulate Air (HEPA) filtration unit which re-circulates air within the space that achieves MERV 13 or better levels of performance.

What is mechanical ventilation?

Ventilation is the intentional introduction of fresh air into a space while the stale air is removed. It is done to maintain the quality of air in that space.

Does the indoor air quality plan make it safe to occupy the building?

In conjunction with other mitigation measures such as mask-wearing and social distancing, the use of filters and air purifiers makes it safer to occupy the building. City Schools indoor air quality plan is based on ASHRAE’s and CDC’s (Center for Disease Control) recommendation to use combinations of filters and air cleaners that achieve MERV 13 or better levels of performance for air recirculated by HVAC (Heating Ventilation and Cooling) systems in high occupancy spaces. Air purifiers are recommended when a filter upgrade is not possible.

How effective are MERV 13 filters? Air purifiers?

Both MERV 13 filters and air purifiers are effective at filtering out coronavirus particles:

  • MERV 13 filters efficiently capture 80-90% of the aerosol that could carry infectious virus particles
  • Air purifiers with HEPA (High-Efficiency Particulate Air) filters efficiently capture 99.97% of the aerosol that could carry infectious virus particles

By themselves, filters and air purifiers are not enough. Face covering, social distancing, and hand hygiene protocols are crucial to providing additional layers of protection.

merv 13 filters

How frequently will filters be changed?

MERV 13 and air purifier filters will be changed quarterly. This is tracked with works orders that are auto-generated through our work order system, SchoolDude.

Who will replace filters and does the district have this capacity?

The district has an in-house team dedicated to changing filters throughout the district year-round and uses mechanical contractors to support the work during routine preventive maintenance.

What is the process for repairing a broken air purifier? What will happen to the classroom/students in that classroom with that air purifiers during the repair?

This is considered an emergency and the school administrator should call their HVAC Project Supervisor and submit a work order in SchoolDude selecting the craft “Indoor Air Quality.” A replacement air purifier will be installed the same day if flagged by 1:00 pm or the next morning before students/staff arrive. Schools should move occupants to one of their identified backup rooms.

What is the process for requesting additional air purifiers?

The school administrator should submit a work order in SchoolDude selecting the craft “Indoor Air Quality" replacement air purifier will be installed within 48 hours from the time that Mechanical Services receives the notification. The work order should be as descriptive as possible.

Is it okay to open windows and doors in a classroom? If windows don't open, are staff students at increased risk?

When weather and air quality conditions allow, check with school administrators about increasing fresh outdoor air by opening windows and doors. Do not open windows and doors if doing so poses a safety or health risk for students (e.g., risk of falling, triggering asthma symptoms).

An air purifier can clean the air with the windows open, but it cannot work as well as it would with the room sealed. Leaving a window open means the air purifier is not just cleaning the air in the room. It must also clean the air entering the room from the outdoors as well and will never have fully purified air inside. When we limit the amount of air an air purifier must clean, we increase its efficiency and the amount of time it will take to freshen an entire room.

How do buildings designed with windows that do not open get fresh air exchange?

The HVAC system installed in the building is designed to provide fresh air exchange.

What additional steps has City Schools taken to improve indoor air quality?

Mechanical Services meets with health and HVAC professionals regularly to advise of recommended practices from the CDC (Centers for Disease Control) and ASHRAE. Mechanical Services also continues to perform routine preventive maintenance on HVAC systems and has made repairs to unit ventilators, which are mechanical devices that circulate conditioned air to spaces (typically classrooms); exhaust fans, which are mechanical devices that removes stale indoor air from a space (typically only found in bathrooms where windows are not operable for safety reasons); and supply fans, which are mechanical devices that deliver air to a space.

Will the old buildings in the district be able to bear the electrical load of multiple air purifiers in instructional spaces?

Yes, buildings will be able to accommodate the additional load from air purifiers. Most HEPA air purifiers consume around 50- 100 watts per hour compared to the general power of a standard light bulb of 60-100 watts, a laptop computer of 50- 100 watts, or an electric heater of 2000-3000 watts. Air purifiers are much more energy-efficient than most popular electric devices.

View the Spreadsheet

In-Person Air Quality Plan