Air Quality for K-12 Schools

Practical guidance for school administrators, athletic directors, and school nurses: when to move recess indoors, how to set AQI thresholds for outdoor activity, how to handle wildfire-smoke days, and how to communicate decisions to families. Sourced from the EPA, CDC, and state-level school guidance.

Why AQI matters more for schools than for the average adult

Roughly 10% of U.S. school-age children have asthma, per the CDC's most recent National Health Interview Survey. In some urban districts the prevalence is closer to 15-20%. Children also breathe faster than adults relative to body weight and spend more time outside during the school day — so a given outdoor AQI delivers a larger inhaled dose per kilogram of body weight.

Schools have a legal duty of care that's stricter than most workplaces. A "moderate" AQI day that an adult worker would shrug off can be a problem for a kindergarten class with five asthmatic students.

Suggested recess and activity thresholds

The EPA's School Air Quality Flag Program publishes a five-color daily flag system. The colors map directly to AQI categories. The thresholds below are aligned with that program and with state-level guidance from California (CDE) and Washington (OSPI).

These are starting points, not federal regulations. Districts in fire-prone or industrial regions often write tighter local thresholds; coordinate with your district nurse and athletic director.

Wildfire-smoke response

Wildfire smoke is the highest-acuity scenario most schools will face. The 2018 Camp Fire pushed Bay Area AQI past 200 for over a week and forced widespread school closures; the 2020 Western fires repeated the pattern; the June 2023 Canadian wildfire smoke event pushed East Coast cities into the same situation for the first time at scale.

• Have a written smoke-shelter plan before fire season. Identify which rooms have the best HVAC, where students will gather, and whether your filtration is MERV-13 or better.
• Pre-stage Corsi-Rosenthal boxes (box fan + four MERV-13 filters; see our build guide) in classrooms with weaker HVAC. Each one delivers roughly 400 CFM of clean air for ~$70 in parts.
• Stock N95s in nurse's offices for after-school dismissal walks. Adult N95s do not fit elementary-age children well; KN95 kid-sized options exist but verify fit before relying on them.
• Have a parent communication template ready. A short, factual notification ("AQI is currently 178 — recess moved indoors today") is far better than silence.

Athletic practice and game decisions

High school athletic conferences are increasingly publishing AQI-based practice cancellation criteria. The California Interscholastic Federation (CIF), Washington Interscholastic Activities Association (WIAA), and the Oregon School Activities Association (OSAA) all have written wildfire-smoke policies; most other state conferences are still on a per-school discretion basis.

A reasonable default for athletic directors without a state-level rule: cancel practice at AQI 151, cancel games at AQI 201. Combined heat + AQI risk is worse than either alone; if WBGT (wet-bulb globe temperature) is also high, drop those thresholds. The AQI and exercise guide covers the physiology and the specific thresholds different athletic governing bodies have adopted.

How Smog Report fits in

Smog Report is a free iOS app that pulls live AQI from the EPA AirNow network. For schools, the practical use cases are:

• School nurse phone: a glanceable widget on the lock screen, plus Live Activities that update without opening the app. Set custom alert thresholds (e.g., notify at AQI 100, 150, 200).
• Athletic director phone: Siri voice queries ("What's the air quality?") for hands-free checks during practice.
• Front-office iPad: a kiosk-style view that auto-refreshes during the school day.

The app is free with no account required. Location data is used only to find the nearest EPA monitor; nothing is sent to a server. For institutional use we don't require any contract or setup — just have staff download from the App Store.

Where to point parents and teachers for more

Some of the most useful background reading on this site for school staff:

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