**2. Materials and methods**

This is an exhaustive cross-sectional study carried out during the two months of August and September 2015, in a Tunisian steel company specialized in the manufacture of springs for heavy vehicles and located in the industrial zone of Teboulba-Moknine of the governorate of Monastir, Tunisia. This company counted 120 workers. A list of names and contact details of all workers was provided by the Human Resources Management Department. Included patients were those who had a job tenure exceeding one year and belonged to production workshops. Exclusion criteria consisted of a participation refusal and a disability or cognitive impairment precluding participation.

The survey was preceded by an individual interview with each eligible worker in order to explain the objectives of the work, its practical progress, guarantee anonymity and obtain informed consent. During the survey, data collection focused on general characteristics, as well as thermal stress measurements. Data analysis was subsequently carried out by the same investigator, using statistical and computer programs.

## **2.1 Data collection**

	- a thermo-hygrometer (TA5 Thermal Anemometers) placed at the workstation at a height of 1.5 m, far from the employees and sheltering the sensor against radiation (sun, oven, etc.). It is a calibrated device with a low response time, a stabilization time of a few seconds enabling punctual measurement of air temperature and relative humidity.
	- a vane anemometer (YK-80AP Vane Anemometer) for measuring air speed. The measurement was discontinuous and the axis of rotation was placed in the direction of the air flow.

• a black globe thermometer (Black globe TP\_875.1/TP\_876.1) placed at the work station at a height of 1.5 m, keeping the employees apart. The measurement time is about 20 min.
