**5. Conclusions**

I have proposed a new model for individual or grouped worker productivity and illustrated it using three sets of data from very different settings. The model is widely applicable to such data and can be fitted to datasets with different properties and levels of completeness using readily available software (Microsoft Excel). This is the first time a model has been proposed that is capable of quantitatively capturing, estimating and displaying not just how average worker productive declines in hot conditions, but also how between-worker variation is affected, a consideration of great epidemiologic importance.

The model might be used as input to assessing (a) health risk to workers and (b) economic risk to industries under climate change, as extreme work environments arise and become increasingly frequent and severe.

**Funding:** This research received no external funding.

**Acknowledgments:** I thank Professor Tord Kjellstrom for collecting and sharing the three datasets, and for helpful comments on early drafts, and the referees for their comments which substantially improved the paper.

**Conflicts of Interest:** The author declares no conflict of interest.
