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Chicago Public Schools Invests $8.5 Million to Provide HEPA Air Purifiers for Every Classroom

04 November 2020

Results of Ventilation and Air Quality Reports Show That All District Schools Have Classrooms That Meet Industry Standards to Resume School-Based Learning

CPS Office of Communications

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CHICAGO — Chicago Public Schools (CPS) today announced that it has invested $8.5 million to purchase more than 20,000 Intellipure HEPA air purifiers for every classroom. The district also released the district-wide and school-by-school results of its ventilation assessments, as well as air quality evaluations, which were conducted by state-certified environmental specialists and show that each school evaluated can support a safe return to in-person learning. CPS is one of the only school districts in the country to conduct comprehensive ventilation assessments of every classroom, and the district has made these reports available for public review at

“Nothing is more important than creating the safest possible in-person learning environments for our students and dedicated staff, which is why we are going beyond public health recommendations to place HEPA air purifiers in every classroom,” said CPS CEO Dr. Janice K. Jackson. “Combined with critical mitigation efforts, such as mask-wearing, readily available hand sanitizer, signage and social distancing, the district’s plan supports a safe return to school.”

“CPS is taking the necessary steps to create the safest possible environment for in-person learning, which is essential to the healthy development of young people in our city,” said Chicago Department of Public Health Commissioner Allison Arwady, M.D. “In private and parochial schools that are in session, as well as other states where in-person learning is occurring, we have seen very little transmission of COVID-19 in those settings.” 

Classroom-Based Air Purification 

While ventilation and air quality standards are not named among the top five key mitigation strategies for schools by the Centers for Disease Control (CDC) — all of which have been implemented by the district — CPS is committed to taking every possible measure to help protect students and staff and be responsive to parent concerns.  

The district’s $8.5 million investment will purchase more than 20,000 Intellipure HEPA air purifiers for every classroom utilized by students as well as staff spaces that do not have mechanical ventilation. These purifiers, which exceed MERV 13 standards and provide more rapid filtration of air than HVAC filters, are capable of ensuring clean, regularly filtered air for classrooms even if mechanical or natural ventilation were not available. 

The Intellipure HEPA air purifiers filter over 99.99% of airborne viruses, bacteria, and mold and follow the Harvard School of Medicine’s Healthy Buildings recommendation to install HEPA filters in classrooms. 

Classroom Ventilation Assessments and Air Quality Evaluations by State-Certified Environmental Specialists Confirm All Schools are Prepared for Safe Occupancy

To ensure that every student who returns to a CPS school is able to learn in a classroom that is safe and properly ventilated, the district carried out a multi-stage assessment of district school buildings. The district used a combination of internal ventilation audits, which involved both classroom-by-classroom assessments of ventilation systems in every district school, as well as independent air quality assessments conducted by state-certified environmental hygienists. Assessments have been completed for nearly all schools and are available at The district’s new web page notes the status of all classrooms, and any classroom that needs repairs or investments will be addressed before students return to those spaces. 

In 2020, the district has invested more than $68 million in mechanical system enhancements and replacements to promote proper ventilation, with an additional $48 million budgeted in FY21 for additional upgrades and repairs.  

In order to be considered ready for occupancy by the district, spaces needed to meet ventilation requirements and schools needed to be deemed as safe for occupancy by an independent state-certified environmental hygienist. 

To meet ventilation requirements, a space must have functioning mechanical ventilation, which is defined as the ability to both move air in and out of the room, or have a functioning window with one or more supplemental air purifiers, depending on the size of the room. Bathrooms are traditionally designed to only utilize air exhaust as a means to exchange air, so an air exhaust is the only requirement for a bathroom to be cleared for use. 

Summary of District Criteria:

  • Air Quality: 
    • State-certified environmental specialist deems a school suitable for re-occupancy. 
  • Ventilation - Classrooms/Spaces: 
    • Functioning Mechanical Ventilation (exhaust and air supply) OR
    • Operable window with air purifiers. 
  • Ventilation - Bathrooms: 
    • Functioning mechanical exhaust. 

Every school report on has a breakdown of the rooms evaluated, including whether it meets the criteria and is ready for re-occupancy. 

Summary of the District-Wide Ventilation Results as of Nov. 2:

  • 94 percent of spaces in school buildings have been cleared (Out of more than 36,000 spaces assessed)
  • 99 percent of classrooms in school buildings have been cleared (Out of nearly 20,000 classrooms assessed)
    • Of all classrooms, 91 percent have functioning mechanical ventilation.
  • No students will be in classrooms that have not been cleared, and all school buildings have classrooms that have been cleared to safely welcome students. 

Summary of District-Wide Indoor Air Quality Results as of Nov. 2:

  • State-certified environmental specialists have determined that all 513 campuses that have been fully evaluated are acceptable for re-occupancy based on the results. Six CPS schools have been under active construction until recently, and their assessments will be completed in the near future and posted to
  • The state-certified environmental specialists evaluated four key metrics in a sampling of areas in each school, which are indicators of mechanical system functions: Airborne particulates, CO levels, temperature and relative humidity. Detailed criteria can be found in the school-based reports online. 
  • Temperature and relative humidity: Temperature and relative humidity are defined by ASHRAE as being generally applicable to comfort and prevention of mold, and while important, are generally not harmful to health. Greater variation outside of recommended ranges among these metrics can be seen across schools while still being considered suitable for re-occupancy by experts.  
    • 98 percent of the approximately 11,000 readings were within the recommended Relative Humidity ranges. 90 percent of schools had all humidity readings within the ideal range. 
    • 76 percent of the approximately 11,000 readings were within the recommended temperature ranges. 26 percent of schools had all temperature readings within the ideal range. 
  • Particulates: 99.7 percent of readings were within the range. Of nearly 11,000 readings district-wide, 35 spaces in 14 schools had areas in the building with particulates outside of the recommended range, primarily due to ongoing construction and maintenance.  
  • CO: 99.99 percent of readings were within the acceptable range. Of nearly 11,000 readings district-wide, only one space at one school had CO ranges in an area outside of the recommended levels. This issue was resolved immediately. 

Additional Critical Measures

In 2020, the district has invested more than $68 million in mechanical system enhancements and replacements to promote proper ventilation and an additional $48 million included in the FY21 budget for critical mechanical system needs. 

In addition to conducting a review of ventilation systems and ongoing upgrades and system enhancements, CPS improved its preventative maintenance program and implemented new procedures to address ventilation in schools. This includes increasing airflow in buildings by operating mechanical ventilation systems two hours before an occupant arrives in the building and two hours after everyone has left the building, which is recommended by ASHRAE guidelines. The district is also replacing all filters in schools. These measures, while not required, are being taken in response to suggested guidance from the CDC, and provides increased circulation of air throughout the buildings. 

While the district has taken a multi-step process to help ensure proper ventilation, it is important to note that the CDC has placed greater emphasis on a variety of other safety measures, all of which the district is prioritizing. Since the district began its initial planning for a potential return to classrooms, Chicago Public Schools has prioritized  the CDC’s five key mitigations for schools:

  • 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 local health department 

Looking Ahead: A Responsibility to be Prepared for In-Person Learning

While the district has not yet determined when school-based learning may resume, the district has a moral obligation to do everything in its power to prepare for a safe return to in-person instruction in order to prevent learning learning loss and promote equity. COVID-19 has had a significant impact on attendance and enrollment among students in pre-k and cluster classrooms, with the greatest impact on Black and Latinx students, and the impact of this will have a profound impact on a generation of students and families if it is not addressed. 

In the near future, the district will provide an update on its goal of resuming in-person learning at some point in the second quarter for students in pre-k and cluster programs. While we do not yet know what the health outlook will be in the days ahead, we will continue to follow the guidance and will only re-open if it is deemed safe to do so by public health officials.

Chicago Public Schools serves 341,000 students in 638 schools. It is the nation's third-largest school district.