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Air quality reporting on iOS

intergalactic.systems

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Re: Air quality reporting on iOS

#61

Post by crazygringo »

brookst wrote: post #51
sandworm101 wrote: post #46

>> I noticed something strange in the iOS weather app: The air quality index seems to be defined relative to the country from which one accesses the air quality map. Yup. And if you look closely the underlying map also sometimes changes based on which country one is standing in (Crimea/Taiwan). Services like iOS are not scientific but consumer and government-focused services. They exist to appease a host of intereste…

Many products have multiple stakeholders. I can't think of a single product that exists "to render dispassionate information" and nothing else.

Really not sure what your point is? The temperature and humidity values that iOS Weather reports are objective and "dispassionate", no? Likewise wind speed and so forth?

AQI is unique in this case, in that it is a color-coded interpretation of combining multiple underlying objective values (PM2.5, etc.). And different governments have chosen different official national schemes for this, according to what they want the population to consider "normal"/green.

Which means that air-polluting industry in one country might lobby for a wider "green" band. Nothing like that is happening around temperature or humidity as far as I'm aware on iOS.

(Though I do believe Beijing had a history of under-reporting official maximum daytime summer temperatures, since people couldn't work outdoors above a certain threshold.)

Re: Air quality reporting on iOS

#62

Post by counters »

crazygringo wrote: post #52
pnpnp wrote: post #38

Earlier quoted context omitted.

Yes - it’s much like now weather forecasting works. Data points may come from 2 places 100 mi apart, but what if someone lives between them? Temperature or other weather data is often an extrapolation based on official weather data collection points, and AQI data is no different. How that data gets extrapolated varies wildly by implementation. edit: Also a fun fact, I live 2000ft above and 50mi from the nearest forec…

Not just forecasting, but reporting values right now . Spatial interpolation is much more non-obvious than you might initially assume, when the data points are coming from arbitrary locations and not a regular grid. For anyone curious, here [1] is a good place to start, or look up "Kriging interpolation". The basic implementation of any kind of continuous temperature estimation is to have a generic equation that rela…

Eh, kriging is overkill relative to the skill you end up with since fine-grain spatial variability in weather can arise from a lot more than the static factors you can pull into such a scheme. This is why objective analysis techniques are typically preferred.

More importantly, high-resolution priors are universally available from weather models, so there is no need to just to ever naively interpolate between weather observation stations very far apart.

One of the reasons that consumer weather apps perform poorly is because in many cases, the companies producing them arbitrarily choose some sort of spatial or temporal resolution requirements, and then throw the problem to an engineer or data scientist who probably doesn't know much more than these simple interpolation techniques (and I absolutely lump kriging into the 'simple' category these days). A modicum of domain knowledge applied here produces a much better product with substantially less effort.

Re: Air quality reporting on iOS

#63

Post by nullindividual »

908B64B197 wrote: post #58
nullindividual wrote: post #55

I should be able to translate what my local government/news says about air quality, just like any other portion of the weather forecast (C, F, etc). Information based on user locality seems like an excellent design.

> what my local government/news says about air quality That's assuming the local government is giving the truth regarding air quality and that their "official scale" is made to reflect reality and not obscure some measurements.

Let's not go there. Unsubstantiated conspiracy theories do not add to this discussion.

Re: Air quality reporting on iOS

#64

Post by counters »

The problem here is twofold.

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.

Re: Air quality reporting on iOS

#65

Post by bluecalm »

nullindividual wrote: post #63
908B64B197 wrote: post #58

Earlier quoted context omitted.

> what my local government/news says about air quality That's assuming the local government is giving the truth regarding air quality and that their "official scale" is made to reflect reality and not obscure some measurements.

Let's not go there. Unsubstantiated conspiracy theories do not add to this discussion.

A Government massaging the data to make the situation look better than it is doesn't qualify as a conspiracy theory. Rather as expected outcome if anything.

The point is that the raw data is always the most valuable. Translating it is an easy task that can be done if the user wishes so.

Re: Air quality reporting on iOS

#66

Post by owl110 »

counters wrote: post #64

The problem here is twofold. 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 ou…

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.

Re: Air quality reporting on iOS

#67

Post by counters »

owl110 wrote: post #66
counters wrote: post #64

The problem here is twofold. 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 ou…

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.

Re: Air quality reporting on iOS

#68

Post by 908B64B197 »

nullindividual wrote: post #63
908B64B197 wrote: post #58

Earlier quoted context omitted.

> what my local government/news says about air quality That's assuming the local government is giving the truth regarding air quality and that their "official scale" is made to reflect reality and not obscure some measurements.

Let's not go there. Unsubstantiated conspiracy theories do not add to this discussion.

> Unsubstantiated

[0] https://www.sciencedaily.com/releases/2021/04/210421151224.h...

[1] https://www.globaltimes.cn/page/202106/1225792.shtml

Re: Air quality reporting on iOS

#69

Post by benatkin »

crazygringo wrote: post #61
brookst wrote: post #51

Earlier quoted context omitted.

Many products have multiple stakeholders. I can't think of a single product that exists "to render dispassionate information" and nothing else.

Really not sure what your point is? The temperature and humidity values that iOS Weather reports are objective and "dispassionate", no? Likewise wind speed and so forth? AQI is unique in this case, in that it is a color-coded interpretation of combining multiple underlying objective values (PM2.5, etc.). And different governments have chosen different official national schemes for this, according to what they want th…

> air-polluting industry

Like producing food? A wider green band than what, the Netherlands map?

I think it's nice to be able to aspire to live in a green area. That one leaves little options, and paints a bleak picture.

Re: Air quality reporting on iOS

#70

Post by [deleted] »

Havoc wrote: post #7

I mean tech is full of conflicting standards. (see relevant xkcd...) In this particular case the actual values just happen to land on the edge of two colours in the scales with very different connotations - orange vs green.

[deleted]
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