Instructions:
- Open the SPO2er iOS app and wait for Health Permission Screen.
- Be sure to grant access to Blood Oxygen.
- Install SPO2er watchOS app on your Apple Watch. Optionally install SPO2er complication.
- When SPO2 data is written to HealthKit on your iPhone, SPO2er will import data (up to 24 hours) and make it available for viewing within the SPO2er app and complication (if present).
- SPO2 data, even from devices that monitor continuously aren’t continuously writing to HealthKit. There will also be a delay between when the measurement is taken, written to HealthKit, imported into SPO2er and when the complication updates.
FAQ:
1. How can I be sure the values are correct?
Open the Health app → search for Blood Oxygen → scroll down → tap Show All Data.
You will see the exact readings stored in HealthKit.
SPO₂er simply displays the same values, both on your iPhone and Apple Watch, using Apple’s data as the single source of truth.
2. Why aren’t there results every hour?
Devices, even those that do continuous SPO2 measurements, don’t write continuously to HealthKit and some devices may not measure SpO₂ continuously or on a fixed schedule.
Blood Oxygen readings occur automatically under certain conditions, which can vary widely:
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You must be still during measurement
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Devices like watches must be snug on your wrist
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Your Skin perfusion, temperature, or motion may affect results
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Some devices sample less often
This is fully controlled by the device, not by SPO₂er.
3. Why is the complication not up to date?
Several factors may cause delay:
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The iPhone must sometimes be unlocked for Health updates to deliver immediately
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Complications update on a schedule set by watchOS
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If the iPhone and Watch are temporarily disconnected, values will sync once they reconnect
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If Health permissions were not granted, SPO₂er cannot access new readings
Opening the SPO₂er iOS app typically forces a refresh if the iPhone is unlocked.
4. Does this show results from 3rd-party devices?
Yes, as long as the device writes Blood Oxygen (SpO₂) samples to Apple Health.
This includes devices like:
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Wellue O₂ rings and fingertip sensors
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Android/medical devices that sync through 3rd-party apps
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Any HealthKit-compatible SPO₂ source
SPO₂er does not care which device recorded the value, it reads the official HealthKit data.
5. Can I enter data manually?
Yes.
On the iPhone app, long-press “Send Latest from Health to Watch” and select Manual Test Value.
Important:
Manually entered values are not written to the Health app.
They are only sent to your Watch for testing or demonstration purposes. If you want to actually manually enter data in HealthKit, the Health app has this feature and those manually entered values will show up in SPO2er
6. Can I highlight values below a certain percentage?
Yes.
In Settings (tap the ⚙️ top left of the iPhone app), you can enable highlighting on both the iPhone and Watch. Once enabled, values below the set percentage will show up red (including high, low, latest, and average).
7. Can I export this data?
Not from SPO₂er.
However, Apple’s Health app allows:
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Exporting your full Health database (.xml file)
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Generating reports using 3rd-party tools
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Sharing data with clinicians, apps, or researchers (where supported)
8. Is SPO₂er data in the cloud?
No. Absolutely not.
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No servers
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No accounts
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No analytics
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No ads
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No tracking
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No cloud storage
All data stays on your iPhone and Apple Watch, inside Apple’s HealthKit and watchOS systems.
We don’t want or collect any personal data… period.
9. What is considered a low SPO₂ value?
This is a medical question and should be answered by a doctor or licensed medical professional.
SPO₂er provides an easy way to view your existing data but does not interpret or categorize it.
10. Is it ok if my SPO₂ drops occasionally?
Only a medical professional can answer this.
Temporary dips can be caused by many things, but SPO₂er does not diagnose abnormalities or medical conditions.
11. You don’t seem to want to answer medical questions?
Correct!
SPO₂er is a viewing tool, not a medical device.
The app:
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Does not analyze trends
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Does not diagnose
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Does not provide recommendations
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Does not judge values as “good” or “bad”
We intentionally avoid medical guidance to ensure safety and clarity.
12. Why does SPO₂er need Health access permission?
SPO₂er cannot see any Health data until you explicitly approve permission in the Health app.
We only request:
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Read access to Blood Oxygen (SPO₂)
And nothing else.
13. Why do I see Cellular Data listed in iOS Settings?
This is shown automatically by iOS for most apps, even those that never access the internet.
SPO₂er does not use cellular data at all, and no data ever leaves your device.
You may turn it off safely.
14. Why can’t SPO₂er trigger a new SPO₂ reading?
Apple does not allow third-party apps to trigger SPO₂ measurements on the Apple Watch.
Only automatic readings or manual measurements taken inside the Blood Oxygen app on the Watch are permitted.
15. Does SPO₂er support 24-hour history?
Yes, SPO₂er shows:
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Last 24 hours of SPO₂ values
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Low / Average / High
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Timestamp list
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Sparkline graph
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History synced to Apple Watch
Values older than 24 hours are still stored in Health, but SPO₂er focuses on the most recent trends.
16. My Watch complication sometimes shows “–” instead of a value. Why?
This occurs when:
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No valid readings exist in the last 24 hours
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Health permissions were not granted
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The phone and watch have not resumed syncing yet
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The Watch is still waiting for updated data after rebooting
Opening the iPhone app usually forces a refresh.
17. Does SPO₂er work if my Apple Watch doesn’t support SPO₂ sensors?
Yes, if you use any device or app that writes SPO₂ values to HealthKit.
Examples:
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Wellue O₂ Ring / O₂ Max
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Other smart rings or fingertip sensors
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Medical-grade devices that sync through companion apps
SPO₂er doesn’t rely on the Watch’s sensor, it relies on HealthKit.
18. Does SPO₂er store my data between devices?
No.
Data lives only in Apple Health, which syncs using Apple’s private systems (if enabled).
SPO₂er simply reads the values locally on each device.
19. What impact does SPO₂er have on my storage?
Short answer: very little.
Full answer (including cache):
On the iPhone, it’s about 10MB for the app and 500KB for the data.
On the Watch, it’s about 3.6MB for the app and 500KB for the data.
The amount of storage for data will be dependent on how many results you have over the 24 hour period, but the data is only pulled from Apple Health and what’s in SPO2er is overwritten every time it’s updated.
20. Can I purge the cache and why would I want to?
Yes, there’s an option for purging the cache in Settings. This doesn’t delete anything in HealthKit. Some people enjoy deleting cache, so we add this feature to our apps. For everyone else, there’s no need. The app overwrites its own database keeping only 24 hours of data and that amount is tiny (~500KB).