1. The heat exposure shall be assessed through “Wet Bulb Globe Temperature Index” (WBGTI) defined by the following equations:
Indoor or outdoor environments with no solar load:
WBGTI = 0,7 tnw + 0,3 tg
Outdoor environments with solar load:
WBGTI = 0,7 tnw + 0,1 ta + 0,2 tg
where:
tnw = natural wet bulb temperature
tg = global temperature
ta = air temperature
2. The appliances that must be used in this assessment are: natural wet bulb thermometer, globe thermometer and common mercury thermometer.
3. The measurements shall be performed in the place where the employee stays, at the height of the most affected body region.
Tolerance Limits for heat exposure, during the intermittent work schedule with periods of rest where the service is delivered.
1. Depending on the ratio obtained, the intermittent work schedule will be defined in Table 1.
Table 1
| INTERMITTENT WORK SCHEDULE WITH RESTING PERIODS IN OWN WORKING PLACE (per hour) |
ACTIVITY TYPE | ||
| LIGHT | MODERATE | HEAVY | |
| Continuous work | up to 30,0 | up to 26,7 | up to 25,0 |
| 45-minute work 15-minute rest |
30,1 to 30,5 | 26,8 to 28,0 | 25,1 to 25,9 |
| 30-minute work 30-minute rest |
30,7 to 31,4 | 28,1 to 29,4 | 26,0 to 27,9 |
| 15-minute work 45-minute rest |
31,5 to 32,2 | 29,5 to 31,1 | 28,0 to 30,0 |
| No work is permitted without the adoption of appropriate control measures | above 32,2 | above 31,1 | above 30,0 |
2. The resting periods shall be considered as the service time for all legal purposes.
3. The activity type (Light, Moderate or Heavy) shall be determined in accordance with Table 3.
Tolerance Limits for heat exposure, during the intermittent work schedule with resting periods in other place (resting place).
1. For the purposes of this item, a thermally wilder environment is considered as a resting place, where a worker rests or performs a light activity.
2. The tolerance limits are given in Table 2.
TABLE 2
| M (Kcal/h) | Maximum WBGTI |
| 175 200 250 300 350 400 450 500 |
30,5 30,0 28,5 27,5 26,5 26,0 25,5 25,0 |
Where: M is the average metabolic rate weighted for an hour, determined by the following formula:
M = (Mt x Tt x Md x Td) / 60
Mt : metabolic rate in the working place
Tt : amount of time in minutes spent in the working place
Md : metabolic rate in the resting place
Td : amount of time in minutes spent in the resting place
WBGTI is the average WBGTI value weighted for an hour, determined by the following formula:
WBGTI = (WBGTIt x Tt x WBGTId x Tt) / 60
WBGTIt : WBGTI value in the working place
WBGTId : WBGTI value in the resting place
Tt and Td : as previously defined
Tt and Td times shall be taken in the most unfavourable time of the work cycle, where Tt + Td = 60 minutes.
3. Mt and Md metabolic rates shall be obtained by referring to Table 3.
4. The resting periods shall be considered as the service time for all legal purposes.
Table 3
| ACTIVITY TYPE | Kcal/h |
| SITTING AT EASE | 100 |
| LIGHT WORK Sitting, moderate movements with arms and trunk (ex.: typewriting). Sitting, moderate movements with arms and legs (ex.: driving). Standing, light work in machine or bench, mainly with arms. |
125 150 150 |
| MODERATE WORK Sitting, vigorous movements with arms and legs. Standing, light work in machine or bench, with some movement. Standing, moderate work in machine or bench, with some movement. In movement, moderate lifting or pushing work. |
180 175 220 300 |
| HEAVY WORK Intermittent work of lifting, pushing or dragging weights(ex.: using shovel). Intense work |
440 550 |
