IQAir vs AccuWeather: Which Air Quality App Should You Trust?
Both apps put an AQI number on your home screen, and both can be right at the same time while disagreeing with each other. The difference isn't accuracy so much as what each one is actually measuring and how it fills the gaps between real monitors. Here's what's under the hood of each, and when that matters.
What IQAir shows
IQAir (through its AirVisual platform) blends two things: government regulatory monitor data, including the EPA's AirNow network in the US, and its own network of low-cost sensors deployed in locations the regulatory network doesn't cover. Where a nearby regulatory monitor exists, IQAir's reading tends to track it closely. Where one doesn't, IQAir interpolates from its own sensor network or nearby stations, which introduces more uncertainty the farther you are from an actual monitor.
IQAir is also well known for its annual World Air Quality Report, which ranks cities and countries globally: a byproduct of running one of the more geographically complete monitoring networks outside the US and Europe.
What AccuWeather shows
AccuWeather's AQI is built primarily as a forecast product, extending its weather-modeling expertise (wind, humidity, temperature, mixing height) to predict pollutant dispersion, blended with available regulatory and satellite data. That forecasting orientation is AccuWeather's real strength: same-day and next-day AQI predictions, which pure monitor-reading apps generally don't attempt. The tradeoff is that a forecast is, by definition, a model output rather than a direct measurement. It can miss a fast-developing local event (a nearby fire, an inversion) that a live regulatory reading would catch immediately.
Why they disagree
- Different jobs. IQAir is oriented toward "what is the AQI right now, blending the best available data"; AccuWeather is oriented toward "what will the AQI be," using weather-model dispersion forecasting.
- Different fill-in methods away from monitors. IQAir leans on its own sensor network; AccuWeather leans on atmospheric modeling. The two methods don't always converge on the same number for the same unmonitored location.
- Update cadence. A forecast-oriented product can lag a fast-moving real-world change (like smoke arriving) until the model catches up; a monitor-blended product reflects the change as soon as the nearest station does.
When to trust which
| Situation | Better fit |
|---|---|
| "What's the AQI right now, at my exact location" | A monitor-grounded reading (AirNow, or IQAir near a regulatory station) |
| "Should I plan an outdoor event tomorrow" | AccuWeather's AQI forecast |
| Comparing air quality across countries or cities globally | IQAir (broadest non-US monitoring footprint) |
| Fast-developing local event (nearby fire, sudden inversion) | A live regulatory reading over any forecast |
What Smog Report uses
Smog Report pulls directly from the EPA AirNow API, the same regulatory backbone both IQAir and AccuWeather reference when a monitor is nearby, with no forecasting or interpolation layer in between. For "what is it right now," that's the most direct path to the number the EPA itself publishes.
Regulatory AQI on your home screen
Smog Report shows real-time AQI from EPA AirNow regulatory monitors with widgets and Live Activities. Free on iOS.
Download for iOSPrimary sources: EPA AirNow · IQAir AirVisual
