The short version: Substrata processes everything on your device. We have no servers, no accounts, no analytics, no ads, and no tracking. We cannot see, access, or collect your data. Your information never leaves your iPhone.
1. Overview
Substrata ("the App") is developed and published by Kynoss Studios ("we," "us," or "our"). Substrata is an environmental health intelligence app for iPhone (iOS 26 and later) that layers environmental data (weather, barometric pressure, noise exposure) against health data from Apple Health to reveal hidden correlations affecting your wellbeing. It includes headache tracking, a statistical correlation engine, and comprehensive weather monitoring. Substrata is not a medical device. It does not diagnose conditions, provide medical advice, or replace professional healthcare guidance.
This Privacy Policy explains what data Substrata accesses, how that data is processed, and your rights regarding your information. We are committed to transparency and to protecting your privacy.
Substrata operates entirely on your device. We do not operate servers, databases, or cloud services. We do not create user accounts. We have no mechanism to collect, receive, view, or store your personal data. The data Substrata works with exists solely on your iPhone, under your control.
2. Noise & Audio Exposure Data
Substrata does not record audio. Ever.
Noise data comes primarily from Apple Watch environmental audio exposure readings via Apple Health. These are pre-processed decibel averages — no raw audio is involved. No audio content is captured, saved, stored, transmitted, or made accessible in any form.
How It Works
Substrata reads noise exposure data from Apple Health, which includes:
- Environmental Audio Exposure (Apple Watch) — averaged dBA readings recorded by your Watch's calibrated microphone, delivered as HealthKit samples approximately every 30 minutes.
- Headphone Audio Exposure (iPhone/Watch) — volume levels when listening through headphones, also delivered as HealthKit samples.
These readings are pre-computed by Apple's hardware and delivered as numerical decibel values through HealthKit. Substrata never accesses raw audio from any source.
What We Store
Substrata stores only timestamped decibel readings (e.g., "72 dBA at 2:35 PM") from HealthKit. These numerical measurements contain no audio content whatsoever.
Your Control
Noise data access is controlled through HealthKit permissions. You can revoke access at any time in Settings > Health > Substrata. The app will continue to function for other features without noise data.
3. Health Data (HealthKit)
With your explicit permission, Substrata reads the following data types from Apple Health via the HealthKit framework:
| Data Type | Purpose | Access |
|---|---|---|
| Sleep Analysis | Sleep quality scoring and correlation with environmental conditions | Read only |
| Heart Rate | Display and correlate with environmental data | Read only |
| Heart Rate Variability (HRV) | Display and correlate with environmental data | Read only |
| Resting Heart Rate | Display and correlate with environmental data | Read only |
| Respiratory Rate | Display alongside health and environmental data (Apple Watch) | Read only |
| Blood Oxygen (SpO2) | Display alongside health and environmental data (Apple Watch) | Read only |
| Wrist Temperature | Display alongside health and environmental data (Apple Watch S8+) | Read only |
| Environmental Audio Exposure | Noise level monitoring (Apple Watch) | Read only |
| Headphone Audio Exposure | Headphone volume monitoring | Read only |
How Health Data Is Used
- Health data is used solely to display your health metrics alongside environmental readings and to calculate statistical correlations for your personal review.
- All health data processing occurs entirely on your device.
- Substrata never writes to or modifies your Apple Health data.
- Health data is never used for advertising, marketing, data mining, or any purpose other than displaying data and statistical correlations directly to you within the app.
- Health data is never shared with third parties.
- Health data is never stored in iCloud or any cloud service.
- Health data is never transmitted off your device.
Your Control
HealthKit access is entirely optional. You choose exactly which data types to share via the standard iOS Health permissions screen. You can modify or revoke access at any time in Settings > Health > Substrata. The app provides useful functionality even without any health data access.
4. Location Data
Substrata offers an optional zone detection feature that uses coarse (approximate) location to help you categorize environments (e.g., "home," "office," "commute").
How Location Is Used
- Location is used only for on-device zone classification.
- Substrata uses coarse location accuracy (reduced/approximate). Precise GPS coordinates are not requested.
- Substrata never stores latitude/longitude coordinates or precise location data. Only the zone label you assign (e.g., "Home") is stored alongside your environmental readings.
- Location data is never transmitted off your device or shared with any third party.
Your Control
Location access is entirely optional and disabled by default. Substrata does not request location permission unless you explicitly enable zone detection. You can revoke location access at any time in Settings > Substrata. The app works fully without location access using manual zone selection.
5. Weather Data
Substrata uses Apple's WeatherKit service to retrieve comprehensive local weather conditions — temperature, humidity, barometric pressure, UV index, wind speed and direction, dew point, cloud cover, visibility, precipitation, sunrise/sunset times, daylight hours, and moon phase — to display alongside your health readings and feed the correlation engine.
- Weather requests are made directly from your device to Apple's WeatherKit service using Apple's first-party API.
- Kynoss Studios does not operate any intermediary server in this process.
- Weather data requests may include your approximate location (if granted) to retrieve locally relevant conditions. This is governed by Apple's Privacy Policy for WeatherKit.
- No personal information is sent to WeatherKit beyond what Apple's API requires to return local weather data.
6. Data Storage & On-Device Processing
All data processing occurs entirely on your iPhone. Substrata has no servers, no cloud infrastructure, no databases, and no backend of any kind. We literally cannot access your data because we have no system to receive it.
Data is stored locally on your device using Apple's SwiftData framework. This data is protected by:
- iOS Data Protection (encrypted at rest, tied to your device passcode)
- App sandboxing (only Substrata can access its own data store)
- Standard iOS security architecture
Substrata does not use:
- iCloud or any cloud storage
- Any third-party SDKs, frameworks, or libraries
- Analytics services (no Firebase, no Mixpanel, no Amplitude, etc.)
- Advertising SDKs or ad networks
- Crash reporting services
- Any form of user tracking or fingerprinting
7. Data Retention & Deletion
Retention Policy
- Raw measurement data (individual decibel readings, health data snapshots, and environmental readings) is retained on your device for 90 days.
- After 90 days, raw data is automatically aggregated into statistical summaries (averages, trends, patterns). The original granular data points are then deleted from local storage.
- Aggregated data (statistical summaries and trend data) is retained indefinitely on your device to preserve your long-term data and trend summaries.
Deletion
- Delete the app: Deleting Substrata from your device permanently removes all associated data. Because no data exists anywhere other than your device, deletion is complete and irreversible.
- In-app data management: You may also clear specific data from within the app's settings.
- There is no server-side data to delete, no account to close, and no request process needed. You have full and immediate control.
8. Data Sharing & Third Parties
Substrata does not share your data with anyone.
- We do not sell your data.
- We do not share your data with third parties.
- We do not transmit your data off your device.
- We do not use third-party SDKs that could collect data.
- We do not serve advertisements.
- We do not engage in data mining or use-based data profiling.
- We do not share data with parent companies, subsidiaries, or related entities (Kynoss Studios is an independent sole developer).
The only network requests Substrata makes are to Apple's WeatherKit service for weather data, using Apple's first-party framework. No personal data or Substrata-specific data is included in these requests.
9. Data Security
Substrata relies on Apple's built-in security infrastructure to protect your data:
- Encryption at rest: All local data is protected by iOS Data Protection, which encrypts data using keys tied to your device passcode.
- App sandboxing: iOS prevents other apps from accessing Substrata's data store.
- No network exposure: Because Substrata does not transmit personal data over any network, there is no risk of data interception, server breaches, or unauthorized remote access.
- No accounts: There are no credentials to steal, no passwords to breach, and no accounts to compromise.
10. Children's Privacy (COPPA)
Substrata is not directed at children under the age of 13. We do not knowingly collect personal information from children under 13.
Because Substrata does not collect, transmit, or store personal information on any server, and because all data remains solely on the user's device, Substrata does not create the data collection risks that COPPA is designed to address. Nonetheless:
- Substrata does not collect personal information from any user, including children.
- Substrata does not require or support account creation.
- Substrata contains no advertising, in-app purchases directed at children, or social features.
- Substrata does not transmit any data to Kynoss Studios or any third party.
If you are a parent or guardian and believe your child under 13 has provided personal information through the app, please contact us at kynossstudios@gmail.com. However, please note that Substrata has no mechanism to receive or access data from any user's device.
11. Your Rights Under GDPR (European Economic Area)
If you are located in the European Economic Area (EEA), the General Data Protection Regulation (GDPR) provides you with specific rights regarding your personal data. We respect these rights, even though Substrata's on-device architecture means we do not act as a data controller or processor of your personal data in the traditional sense — because your data never reaches us.
Legal Basis for Processing
To the extent any on-device processing constitutes "processing" under the GDPR, the legal basis is:
- Consent: You explicitly grant permission for each data type (microphone, health data, location) through iOS permission prompts. You may withdraw consent at any time via iOS Settings.
- Legitimate interest: Processing your data on your own device to provide the app's functionality directly to you.
Your Rights
- Right of access: All data is stored on your device and accessible to you at all times within the app.
- Right to rectification: You can manage and modify your data within the app.
- Right to erasure: You can delete all data by deleting the app, or manage specific data within the app's settings.
- Right to restrict processing: You can revoke individual permissions (microphone, health, location) at any time without affecting other app functionality.
- Right to data portability: Your data is stored locally on your device and is accessible to you.
- Right to object: You can stop all data processing by revoking permissions or deleting the app.
Data Transfers
Substrata does not transfer personal data outside your device. No cross-border data transfers occur because no data is transmitted to any server, anywhere.
Data Protection Officer
Due to the nature of our data processing (entirely on-device, no data collection), we are not required to appoint a Data Protection Officer. For any privacy-related inquiries, please contact us at kynossstudios@gmail.com.
12. Your Rights Under CCPA/CPRA (California)
If you are a California resident, the California Consumer Privacy Act (CCPA) as amended by the California Privacy Rights Act (CPRA) provides you with specific rights.
Information We Collect
Under CCPA/CPRA definitions, Substrata processes the following categories of information on your device only:
- Health information (HealthKit data including noise exposure, sleep, heart rate, with your permission)
- Geolocation data (coarse location for weather and zone detection, with your permission)
- User-reported health events (headache logs entered voluntarily)
However, because all processing occurs on your device and we never collect, receive, or access this information, Kynoss Studios does not "collect" personal information as defined by the CCPA/CPRA.
Your Rights
- Right to know: This Privacy Policy describes all data the app processes. We do not collect additional data beyond what is described here.
- Right to delete: Delete the app to remove all data, or use in-app data management features.
- Right to opt out of sale: We do not sell your personal information. We never have and never will.
- Right to opt out of sharing: We do not share your personal information with third parties for cross-context behavioral advertising or any other purpose.
- Right to non-discrimination: We will not discriminate against you for exercising any of your privacy rights.
- Right to limit use of sensitive personal information: Health data and precise geolocation are considered sensitive under CPRA. You control access to these data types through iOS permissions and can revoke access at any time.
"Do Not Sell or Share My Personal Information"
Substrata does not sell or share personal information. Because no data is transmitted from your device to us or any third party, there is no sale or sharing to opt out of. We fully comply with the CCPA/CPRA without requiring any user action.
13. Apple Platform Disclosures
In compliance with Apple's App Store Review Guidelines and platform requirements:
HealthKit (Guideline 27.0)
- Substrata uses HealthKit data solely to display health metrics alongside environmental data and to calculate statistical correlations for the user's personal review.
- Health data is never used for advertising or use-based data mining.
- Health data is never disclosed to third parties.
- Health data is never sold to any party for any purpose.
- Health data is never stored in iCloud.
- Substrata does not write false or inaccurate data to HealthKit.
- Substrata requests only the minimum HealthKit data types necessary for its functionality.
Required Reason APIs
Substrata uses only Apple's first-party frameworks and does not access any APIs that require declared reasons beyond those already disclosed in this policy and in the app's App Store privacy nutrition label.
App Tracking Transparency
Substrata does not track users across apps or websites owned by other companies. The App Tracking Transparency framework is not used because no tracking occurs.
App Privacy Nutrition Label
Substrata's App Store privacy nutrition label accurately reflects that the app does not collect data linked to user identity and does not track users.
14. Changes to This Policy
We may update this Privacy Policy to reflect changes in the app's functionality or legal requirements. When we make changes:
- The "Last Updated" date at the top of this page will be revised.
- Material changes will be communicated through the app or its App Store listing.
- Continued use of Substrata after changes constitutes acceptance of the updated policy.
We encourage you to review this policy periodically. This policy will be updated at least annually.
15. Contact Us
If you have questions about this Privacy Policy, your privacy rights, or Substrata's data practices, please contact us:
- Email: kynossstudios@gmail.com
- Developer: Kynoss Studios
- Support Page: Substrata Support
We will respond to privacy inquiries within 30 days.