Air Quality

Current conditions from

MVWSD recognizes that poor air quality due to wildfire smoke and extreme heat are conditions that are happening with more regularity.

The District has developed guidelines based on stakeholder input.  On bad air days, decisions about actions, activities cancellations or school closure will be made based on EPA’s AQI monitoring tools at and the MVWSD Air Quality Index Chart. While there are other air quality monitoring systems, we'll use MVWSD will use the Bay Area Air Quality Management District as secondary source for air data.

MVWSD Air Quality Index Chart   (Click here for Spanish)
Air quality index chart

It’s important to note that modifications to school activities would not come into effect until Level Orange (101-150) “unhealthy for sensitive groups” as reported by AirNow.


• A network of monitors maintained and operated by trained government agencies.
• It is recommended by many air districts, the California Air Resources Board, and U.S. EPA.
• AirNow monitors form a network to track regional air quality. Pollutants like smoke tend to be well-mixed in the atmosphere and may be adequately represented by these monitors, even if a monitor is not in the same neighborhood as a school.
• Uses highly accurate tools that are regularly monitored for quality control by U.S. EPA. Tools remain accurate at all levels as opposed to personal sensors like Purple Air, which overestimate (especially at AQI of 150 or higher).
* readings are recommended by the Santa Clara County Office of Education, the California School Boards Association and the California Department of Education.

Why not Purple Air?

* Purple Air tends to overestimate (especially at AQI of 150 or higher).
* Sensors are not maintained and operated by trained agencies.
* Changes to settings by the user are required to receive comparable data (See "Understanding PurpleAir vs. Measurements of Smoke Pollution")
* is piloting a map that shows its interpretation of wildfire smoke data using PurpleAir sensors. Click here to see AirNow Fire and Smoke Map.

MVWSD indoor ventilation
HVAC equipment was replaced and improved this summer in mechanical closets and in classrooms, offices, MUR across the campuses. Our schools’ HVAC systems have been updated to include MERV-13 filters, which is the highest-grade filter available for our units, or air purifiers with filtration ratings at least as high as the MERV-13.  Additionally, each classroom is equipped with a HEPA filter. We continue to consult with HVAC engineers to maximize the quality of indoor air as much as possible.

When AQI is high these tips are useful to protect against  smoke and COVID-19:  

  * Stay at home as much as possible with windows and doors closed until smoke levels subside.
  * Limit trips outside while air quality remains unhealthy.  
  * Continue to wear a face covering to protect yourself and others from COVID-19.  
  * Minimize the amount of time you are active outdoors.   
  * Set air conditioning units and car vent systems to re-circulate to prevent outside air from moving inside.  
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