By PulsHealth. Updated
Research reviewed .
Does UV Exposure record a dose or an index?
Apple defines UV Exposure as a discrete UV index value for the sample's duration, stored using count units. The name does not mean a running total of radiation dose. A value of 5 is an index level, not five minutes outdoors or five units of absorbed radiation. Apple documents these semantics.
What do UV index levels mean?
The UV index describes the potential for harm from solar UV radiation. EPA's guidance groups it into low 0–2, moderate 3–5, high 6–7, very high 8–10 and extreme 11+. These are environmental risk categories, not a distribution measured from the database or a personal safe-exposure timer. Skin, protection and actual surroundings matter.
| Quantity | What it describes |
|---|---|
| UV index | UV intensity represented for an interval |
| Sample duration | Time the source associates with that index |
| Time in daylight | A different cumulative time quantity |
| Radiation dose | Not directly supplied by this type |
Can UV index samples be added together?
No: a daily sum of UV index values mainly changes with recording frequency. A peak can describe the highest recorded index, while a time-weighted average needs adequate intervals, duplicate handling and explicit gap rules. Even index multiplied by time is an analytical proxy with assumptions, not a measured personal skin dose.
Check whether the source provided a local sensor measurement, a forecast or another estimate. A timestamp alone does not establish where the user was, whether they were in shade, or whether sunscreen or clothing changed actual exposure. HealthKit does not promise a fixed sampling cadence for this identifier.
How does this relate to daylight or outdoor activity?
Time in Daylight records duration, without supplying a matching UV index. Matching an outdoor workout with UV records can provide descriptive context only when both have credible coverage. Neither daylight time nor a workout label can establish UV dose or vitamin D production.
What did the coverage review find?
The reviewed 365-day example-data window contained no samples, stored aggregates or workout-series points for this type. Value distributions, unusual readings, recording cadence and related-data comparisons could not be measured. No empirical figure is presented; missing database rows do not establish missing records on the phone.
Does PulsHealth collect this type?
The current PulsHealth sync catalog includes this type in count. Database coverage and Apple Health availability are separate questions.
Understanding your records
Recording frequency, source and coverage affect what you can conclude from this data. Read the recording guide.
- One record
- Unitless UV index represented using HealthKit count units; not minutes or a cumulative radiation dose.
- Frequency
- Source-dependent contributions, spot readings or recorded intervals; no empirical cadence was available.
- Context
- Interpret timing and source method for the specific measurement; timestamp overlap does not establish shared session identity.
- Coverage and gaps
- No observations in the reviewed reporting window; database absence is not a zero reading or proof of absence on the phone.
- Summaries
- Discrete values are not cumulative totals. Use compatible units, durations, coverage and source methods for summaries.
- Metadata
- Optional source metadata does not establish complete measurement method or context; no records were available to inspect.
Recording guidance reviewed 2026-10-14