First, many countries have their own laws and policies regarding air quality exposure. Often times these regulations use metrics about time-average exposure (e.g. the annual average 8-hr maximum ozone concentration) and can't trivially be converted between agencies. It causes very negative user experiences when your air quality summary disagrees with what a regulatory agency is putting out to the public due to a measurement technicality - much easier just to localize the data in the same way you'd localize the rest of the UI.
Second, we're stuck with AQI and similar indices because air quality is a multi-faceted problem with different components measured wildly differently. For instance, PM2.5 and PM10 are typically reported in ug/m^3 - but who actually knows what these measurements mean? What's the difference between 15 and 30 ug/m^3? It's very far outside of the experiences that many individuals have, so end users really struggle to interpret these values, even when you translate them into simple "low"/"medium"/"high" categories. Then of course gas-phase pollutants are typically reported in volume concentrations like parts-per-billion or parts-per-million. Aside from the fact that these values are very commonly misinterpreted as much smaller than they actually are, the difference in units adds another bit of complexity into users interpreting what they're seeing.
A well-designed air quality index could factor our all these challenges. I definitely h/t Breezometer for their attempts there, even if it is generally poorly received. But it's a very challenging problem no matter how you slice it.
These are very good points but at least Apple could give the user a choice to report air quality consistently when traveling. At the core, this is not a measurement problem (the underlying data is likely the same) but it is a user experience issue since a user cannot use the color coding as a way to compare different scales across locations.
Well, the underlying data might not actually be the same.
One country may lump in PM10 into their AQI, so if there is a dust storm or similar event, the AQI could spike. Other countries may only include PM2.5 or not include PM at all, which wouldn't capture the dust storm.
> many countries have their own laws and policies regarding air quality exposure. Often times these regulations use metrics about time-average exposure (e.g. the annual average 8-hr maximum ozone concentration) and can't trivially be converted between agencies. It causes very negative user experiences when your air quality summary disagrees with what a regulatory agency is putting out to the public due to a measurement technicality
Ultimately, why not simply compute it and give the user a warning that the local measurement isn't compatible with proper AQI measurement?
Also, does my body magically changes the way it reacts to air pollution as soon as I take my first step abroad?
Likely incompatible measurements combined with regulatory laws regarding reporting.
Remember when Donald Trump drew on a NOAA map and multiple outlets reported that was essentially a felony?
Imagine doing that all over the world. You're gonna find a couple jurisdictions not taking kindly. Remember, this is Apple, any negative pushback is a PR problem disguised as UI to it's walled garden.
First, many countries have their own laws and policies regarding air quality exposure. Often times these regulations use metrics about time-average exposure (e.g. the annual average 8-hr maximum ozone concentration) and can't trivially be converted between agencies. It causes very negative user experiences when your air quality summary disagrees with what a regulatory agency is putting out to the public due to a measurement technicality - much easier just to localize the data in the same way you'd localize the rest of the UI.
Second, we're stuck with AQI and similar indices because air quality is a multi-faceted problem with different components measured wildly differently. For instance, PM2.5 and PM10 are typically reported in ug/m^3 - but who actually knows what these measurements mean? What's the difference between 15 and 30 ug/m^3? It's very far outside of the experiences that many individuals have, so end users really struggle to interpret these values, even when you translate them into simple "low"/"medium"/"high" categories. Then of course gas-phase pollutants are typically reported in volume concentrations like parts-per-billion or parts-per-million. Aside from the fact that these values are very commonly misinterpreted as much smaller than they actually are, the difference in units adds another bit of complexity into users interpreting what they're seeing.
A well-designed air quality index could factor our all these challenges. I definitely h/t Breezometer for their attempts there, even if it is generally poorly received. But it's a very challenging problem no matter how you slice it.