USAirQMinder Support

The current U.S. Air Quality Index for wherever you are. Questions, problems, or ideas? Email wjfrench@proton.me and you'll get a reply, usually within a couple of days. Answers to the most common questions are below.

Getting Started

Is there anything to set up?

No. Allow location access when the app asks, and the reading appears. There is no account, no sign-in, and no API key to obtain.

Readings

What do the numbers mean?

The EPA's Air Quality Index runs from 0 to 500 in six bands, and the app shows the band's colour and its official health message:

• 0–50 Good — little or no risk.
• 51–100 Moderate — acceptable; a risk for people unusually sensitive to air pollution.
• 101–150 Unhealthy for Sensitive Groups — sensitive groups may feel effects; the general public is less likely to.
• 151–200 Unhealthy — some of the general public may feel effects; sensitive groups more seriously.
• 201–300 Very Unhealthy — health alert; risk is increased for everyone.
• 301+ Hazardous — health warning of emergency conditions.

Where do the numbers come from?

From the Copernicus Atmosphere Monitoring Service (CAMS) global forecast, served by Open-Meteo. This is a model: it estimates pollutant concentrations across a grid covering the whole world, rather than reading them from an instrument near you. The index and its six bands are the EPA's, so a number means what it means anywhere else you see a U.S. AQI — but the figure behind it is a forecast, not an EPA measurement.

How is that different from what airnow.gov shows?

airnow.gov publishes readings from actual EPA, state, local and tribal monitors. This app shows a forecast for your coordinates. The two usually agree closely, and can disagree during fast-moving events such as wildfire smoke, where a model may lag what a monitor is recording. If a specific number matters to you — for a health decision, or during a smoke event — check airnow.gov.

Why does it show one number when there are six pollutants?

The AQI is worked out separately for each pollutant — ozone, PM2.5, PM10, NO₂, SO₂, CO. The figure everyone calls "the AQI" is the worst of them, and that is the one shown large, with the pollutant responsible named underneath. The others appear in the row below it. A pollutant with no figure is left out rather than shown as zero.

How often does it update?

The figures step hourly, so checking more often than that won't get you newer numbers. The app checks on the schedule you pick in Settings while it is open, and every time you return to it. The "Modelled for" line tells you which hour the figure applies to.

The Widget

How do I add it?

Touch and hold an empty part of your home screen, tap Edit then Add Widget, search for USAirQMinder, and choose a size. Small and medium are both available.

It says "Open USAirQMinder to update".

The widget's last refresh failed — usually no network, or location unavailable at that moment — and the cached reading it falls back on has gone stale. Opening the app fetches a fresh one and the widget follows.

The widget asks for location separately.

That is iOS. A widget is a separate process from the app, so it needs its own permission to use your location. Allowing it lets the widget refresh on its own instead of only when you open the app.

It hasn't updated in a while.

iOS decides when widgets may refresh, based on battery, usage patterns and how often you look at it. The app asks for roughly hourly; the system may allow less. Opening the app always brings both up to date.

Privacy

No accounts, no analytics, no advertising, and no server of ours for the app to talk to. Your approximate location goes to Open-Meteo to fetch the figures, and to Apple's built-in geocoder to turn your coordinates into a place name. Nowhere else. The full detail is in the privacy policy.

Data Source

Figures come from the Copernicus Atmosphere Monitoring Service (CAMS), served by Open-Meteo. The index and its categories follow the U.S. Environmental Protection Agency's published AQI scale. USAirQMinder is not affiliated with or endorsed by the EPA, Open-Meteo, or CAMS.