---
title: ProcessInfo.ThermalState.critical
framework: foundation
role: symbol
role_heading: Case
path: foundation/processinfo/thermalstate-swift.enum/critical
---

# ProcessInfo.ThermalState.critical

The thermal state is significantly impacting the performance of the system and the device needs to cool down.

## Declaration

```swift
case critical
```

## Discussion

Discussion The system takes significant steps to reduce thermal state. Fans are running at maximum speed. Reduce usage of the CPU, GPU, and I/O such as Bluetooth or network to the minimum level required for user interaction. If possible, stop using peripherals such as the camera, flash, microphone, and speaker.

## See Also

### Constants

- [ProcessInfo.ThermalState.nominal](foundation/processinfo/thermalstate-swift.enum/nominal.md)
- [ProcessInfo.ThermalState.fair](foundation/processinfo/thermalstate-swift.enum/fair.md)
- [ProcessInfo.ThermalState.serious](foundation/processinfo/thermalstate-swift.enum/serious.md)