Air quality and your planned run
Running in poor air quality
By Iustin Nita · Updated
Check the pollutant and local advice before running in poor air quality. EPA guidance changes with the AQI band, your sensitivity, and how long or hard you plan to run. The U.S. scale below is guidance, not personal clearance.
An air-quality alert arrives with a number, while your plan still says intervals or a long run. That number needs a source and a time. Check whether it is a current report or a forecast for the hour you intend to run, and which pollutant is driving it.
This page explains the U.S. AQI scale. Other countries use different indices. It does not show a live local reading, identify the pollution on your route, or calculate a pace that makes exposure acceptable.
The six U.S. AQI bands
EPA Tables 1 and 5, summarized for particle pollution and ozone. Sensitive groups differ by pollutant, as explained below. Follow the full local advisory for your situation.
| U.S. AQI | EPA category | Particle pollution and ozone activity guidance |
|---|---|---|
| 0-50 | Good | No EPA activity restriction. |
| 51-100 | Moderate | Unusually sensitive people: consider reducing duration or intensity. |
| 101-150 | Unhealthy for Sensitive Groups | Sensitive groups: reduce duration and intensity, and add breaks. |
| 151-200 | Unhealthy | Sensitive groups: reschedule or consider indoor activity. Others: shorten and ease off. |
| 201-300 | Very Unhealthy | Sensitive groups: avoid outdoor exercise. Others: limit it; avoid long or hard sessions with ozone. |
| 301+ | Hazardous | Everyone: avoid outdoor exercise. Sensitive groups with particles: keep indoor activity light. |
The pollutant changes who is sensitive
For particles, EPA names heart or lung disease, older adults and children; pregnancy also matters during smoke events. For ozone, it names lung disease, older adults, children and people active outdoors. A runner can belong to that last group without a diagnosis.
Change the session, then check again
Illustrative decisions, not tested prescriptions: in the Unhealthy band, replace intervals with shorter, easier activity if local advice permits. A sensitive runner facing particles in that band can reschedule or consider activity indoors with cleaner air.
For smoke, check AirNow and your local public-health advisory, including their indoor-air and mask guidance. This page does not provide a mask recommendation or a protection estimate for running. A different route needs its own local air-quality information.
RunWeather warnings are a separate policy
RunWeather adds an air-quality advisory from U.S. AQI 151. At 200 or higher, its conservative policy suppresses outdoor pace advice. These are app rules, not individual medical cutoffs. The EPA Hazardous category begins at 301, so the app's stop threshold must not be read as that official category.
Air quality is a warning input, not an AQI-to-pace equation. The shared pace model has no pollution coefficient that turns an alert into a percentage slowdown. Leaving a pace target visible below the suppression threshold does not certify that the run suits your health or the local advisory.
What the calculator knows about the air
The public Run Score calculator requests overall U.S. AQI from Open-Meteo. Its air-quality forecasts come from Copernicus Atmosphere Monitoring Service models. They represent regional modeled conditions, rather than a sensor following your running route.
The current calculator request does not include pollutant concentrations or the individual pollutant indices, so its AQI value cannot identify whether particles, ozone or another pollutant drove the number. Check an official local report for the pollutant, reporting area and observation time. A forecast hour is a valid time for an estimate, not a new measurement.
Missing AQI means unavailable. The current score model gives missing AQI no air-quality penalty, and AQI is not among its critical confidence fields. A favorable Run Score, including one marked high confidence, therefore cannot establish that clean air was measured. Check the separate air-quality information before making the pollution decision.
Sources and guidance
Running in poor air quality: FAQ
Does a good Run Score mean the air was measured as clean?
No. The calculator uses a modeled overall AQI forecast, and an unavailable AQI value does not currently lower its critical-input confidence. The score cannot replace a current local air-quality report.
Can RunWeather turn AQI into a safer target pace?
No. There is no AQI-to-pace coefficient in the shared pace model. RunWeather raises an advisory at 151 and suppresses outdoor pace advice at 200 under its own conservative policy. Follow official local advice for the pollution decision.
Does the calculator tell me which pollutant is causing the alert?
No. It requests overall U.S. AQI, without pollutant concentrations or individual pollutant indices. The driving pollutant is unknown from that request. Check your official local report for that detail and its reporting time.
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