---
title: HMCharacteristicValueAirQuality.unknown
framework: homekit
role: symbol
role_heading: Case
path: homekit/hmcharacteristicvalueairquality/unknown
---

# HMCharacteristicValueAirQuality.unknown

The air quality is unknown.

## Declaration

```swift
case unknown
```

## See Also

### Air Quality

- [HMCharacteristicValueAirQuality.excellent](homekit/hmcharacteristicvalueairquality/excellent.md)
- [HMCharacteristicValueAirQuality.good](homekit/hmcharacteristicvalueairquality/good.md)
- [HMCharacteristicValueAirQuality.fair](homekit/hmcharacteristicvalueairquality/fair.md)
- [HMCharacteristicValueAirQuality.inferior](homekit/hmcharacteristicvalueairquality/inferior.md)
- [HMCharacteristicValueAirQuality.poor](homekit/hmcharacteristicvalueairquality/poor.md)