# PHS

> Calculates and illustrates predicted heat strain for thermal risk assessment. (iPhone/iPad app by Kelly Johnstone.)

- Source: https://appshunter.io/ios/app/phs/id1148768952 (this page in markdown: same URL + `.md`)
- Developer: [Kelly Johnstone](https://appshunter.io/developer/1148768951)
- Category: Utilities
- Price: Free
- Rating: 5.00/5 from 1 App Store ratings
- Age rating: 4+
- Requires: iOS 8.0 · 4 MB
- Languages: American English
- Released: 2016-09-12
- Data updated: 2026-07-07
- Monetization: free
- User reviews in markdown: https://appshunter.io/ios/app/phs/id1148768952/reviews.md

## What is PHS?

The PHS application analyses and interprets thermal risk using calculations of predicted heat strain. The application applies predicted heat strain formulae outlined in ISO 7933:2004 Ergonomics of the thermal environment, to provide a graphical illustration and summary of predicted heat strain based on user entered data. The application may also be used to analyse methods of reducing or managing thermal risk associated with a task or environment. However, the application is to be used as a guide only. It does not provide safe/ unsafe working limits. A number of factors are not included in this assessment, such as: employee health conditions and the use of high level PPE (impermeable suits). There are limitations to the predicted heat strain calculations, once you approach the defined parameters outlined in Table A.1 within ISO 7933:2004.

For more information about the application and to access a downloadable user guide for the application visit the Website at http://ergonomics.uq.edu.au/PHS/index.html.

The development of this application was funded via a joint study between The University of Queensland, Faculty of Science and Rio Tinto.

Developed at Stellar Science LTD.

## Key features

- Thermal risk analysis
- Predicted heat strain calculations
- ISO 7933:2004 formula application
- Graphical illustration of heat strain
- Thermal risk management guidance


## Frequently asked questions about PHS

### What is PHS used for?

PHS is used to analyze and interpret thermal risk by calculating predicted heat strain using formulas from ISO 7933:2004. It provides graphical illustrations and summaries to help manage thermal risks associated with tasks or environments.

### Is PHS free to use?

Yes, PHS is available for free. It does not have any in-app purchases or advertisements.

### What devices does PHS support?

PHS is supported on iPhone and iPod devices.

### How often is PHS updated?

The latest version of PHS is 3.2, which was last updated on December 3, 2019. Information on future update frequency is not available.

### What are the limitations of PHS?

PHS is intended as a guide only and does not provide safe/unsafe working limits. It does not account for factors like employee health conditions or the use of high-level PPE, and calculations have limitations near defined parameters in ISO 7933:2004.

### What is the age rating for PHS?

PHS has an age rating of 4+, making it suitable for a wide range of users.

### Where can I find more information about PHS?

More information about PHS, including a downloadable user guide, can be found on its website at http://ergonomics.uq.edu.au/PHS/index.html.

### Does PHS have ads?

No, PHS does not contain advertisements. It is a completely ad-free application.

## Version history (last 5 releases)

### 3.2 — 2019-12-03

Temperature calculation issue resolved.

### 3.1 — 2018-07-23

Export Reports as PDF

### 3.0 — 2018-07-13

Minor bug fixes.

### 2 — 2018-02-15

Minor updates for iOS 11

### 1.0 — 2016-08-31

This update is signed with Apple’s latest signing certificate. No new features are included.

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*Data collected daily from the US App Store and indexed by [AppsHunter](https://appshunter.io/). User reviews are verbatim App Store reviews. Ratings, prices and chart positions refresh continuously; this snapshot is from 2026-07-07.*