Can I go outside? (AQI safety check)

Enter the current AQI (or use your location), your planned activity, and any sensitive-group flags. Guidance follows EPA's activity recommendations by AQI level.

Guidance paraphrased from EPA. Not medical advice — see disclaimer.

What this calculates

The tool takes three inputs — the current AQI, what you intend to do, and whether you are in a sensitive group — and returns EPA's own activity guidance for that combination. It is a lookup, not a model: there is no hidden formula weighting your inputs. The AQI bands it keys on are the 2024 EPA breakpoints, the same table the rest of this site uses, so the advice never disagrees with the number shown at the top of a city page.

"Sensitive group" is EPA's category, not ours. It covers people with asthma or other lung disease, people with heart disease, children, older adults, and people who are pregnant. Outdoor workers and anyone exercising hard are exposed to far more air per hour than the guidance assumes, which is why the activity input changes the answer as much as the AQI does.

Where the guidance comes from

The recommendations are EPA's, published with the AQI itself and reproduced on AirNow's AQI basics. We paraphrase for length but do not soften: where EPA says "avoid", this tool says avoid. The underlying category names and their health language live in one file (lib/aqi/categories.js) shared by every page on the site, so a change is made once and cannot drift between the tool and the city pages.

What this does not tell you

It does not know where you are standing. AQI is reported for a monitoring area that can be tens of miles across. Smoke is not evenly distributed inside one: a valley floor, a spot downwind of a fire, or a street canyon at rush hour can be substantially worse than the number for the area as a whole.

It does not know how long you will be out. The guidance assumes ordinary exposure. Twenty minutes at AQI 160 is not the same as a four-hour shift at AQI 160, and no single-number answer can capture that.

It is not medical advice, and it cannot override a treatment plan. If you have a condition that smoke affects, your clinician's instruction wins — see our medical disclaimer.

It uses the current reading, not a forecast. During a moving plume the AQI can climb faster than an hourly observation reflects. If the trend line on your city page is rising steeply, treat the current number as optimistic.

A worked example

It is 4 p.m. and your city page reads AQI 138 (Unhealthy for Sensitive Groups), dominant pollutant PM2.5. You have mild asthma and were going to run 5 miles.

At 101–150 EPA's guidance for sensitive groups is to reduce prolonged or heavy exertion, take more breaks, and reschedule strenuous activity. A hard 45-minute run is squarely "prolonged and heavy": you would be moving perhaps ten times your resting air volume, for most of an hour, through the part of the day when the plume is thickest. The tool returns "reschedule".

The same 138 with no sensitive-group flag and a 15-minute walk to the shop returns "fine, but watch for symptoms" — the identical AQI, a different answer, because the exposure is different. That is the whole point of asking three questions instead of one.