AQI Activity Calculator
Air quality category and outdoor exertion guidance from the AQI number.
What it does
The Air Quality Index compresses pollution into one number with one color: green through maroon, good through hazardous. Outdoor exertion guidance splits by group because children, older adults, and lung patients feel smoke first.
The tool above takes the AQI number. It returns the category with guidance for sensitive groups and everyone else beside them.
The default of 120 reads Unhealthy for Sensitive Groups (Orange): sensitive groups shorten and ease off while everyone else takes more breaks. At 45 the same tool reads Good with no limits.
The bands follow EPA AirNow activity guides with particle and ozone booklets matching each line. Both step guidance at 50, 100, 150, 200, and 300 with color names attached.
How to use
- Read the current or forecast AQI from AirNow.
- Enter the number 0 to 500.
- Read the category first with its color.
- Sensitive groups follow their line strictly.
- Everyone else follows theirs, watching symptoms.
Formula
- USG
- Unhealthy for Sensitive Groups, the orange band.
- sensitive
- Lung and heart disease, children, older adults, outdoor workers.
- 100
- The pollutant standard line; above it agencies name groups.
Ozone and particle guides differ slightly in wording; this page uses the shared activity spine. Wildfire smoke follows particle guidance at the same numbers.
Worked example
Example: AQI 120
Default: AQI 120.
- Band: 101 to 150 is Unhealthy for Sensitive Groups (Orange).
- Sensitive: shorten and ease off exertion.
- Everyone else: OK outside with more breaks.
- Morning scheduling helps for ozone driven days.
- Tool shows the orange category with both guidance lines.
Reference table
| AQI | Category | Guidance |
|---|---|---|
| 0-50 | Good (Green) | No limits |
| 51-100 | Moderate (Yellow) | Unusually sensitive ease off |
| 101-150 | USG (Orange) | Sensitive groups shorten exertion |
| 151-200 | Unhealthy (Red) | Everyone curbs long exertion |
| 201-300 | Very Unhealthy (Purple) | Avoid outdoor exertion |
| 301+ | Hazardous (Maroon) | Everyone indoors |
Limits
- Guidance, not medical advice; conditions rule.
- Ozone peaks afternoons; smoke lingers all day.
- Indoor air tracks outdoor without filtration.
- Masks help particles, little for ozone.
Common mistakes
- Exercising hard through orange air with asthma.
- Reading one pollutant while another spikes.
- Trusting morning clarity on ozone days.
- Skipping rescue medicine on smoky runs.
- Sealing homes without cooling in heat.
Try it yourself
Quick checks. Answers sit tucked under each question.
AQI 45?
Good (Green): no limits for anyone.
AQI 250?
Very Unhealthy (Purple): avoid all outdoor exertion.
Kids practice at 130?
USG: more breaks, less intensity, watch symptoms.
Questions
What AQI is safe to run in?
Under 100 for most; sensitive runners ease off past 50 and cut back past 100.
What does 150 mean?
Top of orange: sensitive groups curtail, everyone else shortens exertion.
Who are sensitive groups?
Lung and heart disease, children, older adults, outdoor workers.
Morning better?
For ozone, yes: it builds afternoons. Smoke ignores the clock.
Do masks help?
N95 style helps particles; little against ozone gases.
Where do I check AQI?
AirNow publishes current and forecast AQI by location daily.