Classroom Air Quality

Testing, Filters and Air Changes

Before the pandemic, you might never have given much thought to the heating and ventilation (HVAC) systems in SPS schools. Now families and staff share a focus on how those systems function.


Every classroom has been tested to measure air change rates and air quality. SPS is following Washington State Department of Health (DOH) guidelines regarding air filters and exceeding DOH guidelines on effective air changes per hour in schools.


Building HVAC systems that could accept MERV 13 filters have had them installed. Those schools where MERV 13 filters could not be installed have been provided with a stand-alone, portable, High Efficiency Particulate Air (HEPA) filtration unit to help cleanse the air.

Effective Air Change

The recommendation is to provide five effective air changes per hour based upon the cubic volume of the room. SPS is balancing its existing HVAC systems to provide six air changes per hour. Classrooms or schools where that cannot be achieved have been provided a stand-alone, portable HEPA filtration unit.

Continued Monitoring

SPS staff and a third-party firm are conducting onsite testing to measure the particulate level of each school. The testing program is designed to meet the goal of delivering adequate clean air to provide a safe environment by removing aerosols capable of carrying the COVID 19 virus. In addition to the testing that occurred before in-person classes began, additional testing is currently happening now that buildings are occupied. Testing will be done again when changes are made to systems that impact airflow.

(Seattle Public Schools, Sept. 15, 2021)