Part#3.7: Work Practice – Using Different Work-rest Rate under Different Heat Index per

Figure ‎4-35: Number of responses for work/rest rotation rate under heat index periods 27°C-31°C and 32°C-38°C

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Figure ‎4-37: Number of responses for work/rest rotation rate under heat index >54 °C

In this part, the work/rest ratios are going to be investigated with different heat index periods to check which ratio is suitable and practical for use in the real physical work conditions where there are four work rate groups; resting (work with hands only), moderate (work with arms and hands), high (intense arms and trunks work), and very high (work activity cannot be sustained for long periods). The results are illustrated below:

Heat index (27°C – 31°C) & (32°C -38°C)

1. Resting (work with hands only):

Most of the respondents agreed to use the work/rest ratio 50/10 where 113 respondents agreed to use this ratio for the heat index 27°C-31°C and 93 respondents agreed to use this ratio for heat index 32°C-38°C. 33 of the respondents agreed to use the work/rest 40/10 ratio for the heat index 27°C-31°C and 55 of the respondents agreed to use this ratio for the heat index 32°C-38°C.

100 2. Moderate (work with arms and hands):

Here, the results are almost equal, the respondents agreed to use both the work/rest 50/10 or 40/10, where 84 person agreed to use the work/rest 50/10 for heat index (27°C-31°C) and 65 people agreed to use the work/rest 40/10 for the heat index period. Also, 72 people agreed to use the work/rest 50/10 or 40/10 for (32°C -38°C). 3. High (intense arms and trunks work):

The resonse context to this part was answered differently, compared with resting moderate rate work because people believe that once the rate of the work increases, the rest period should be more than the one who is working with less rate. About 90 people per each heat index perions agreed to use the work/rest 40/10 rate and about 50 people per each heat index believe that we should use the work/rest 50/10 ratio for both heat index.

4. Very high (work activity cannot be sustained for long periods)

The answers for this work rate are almost similar to the responses of high work rate, but the difference is that the rseponses increased for more than 100 responses to use the work/rest 40/10 for this type of work and decreased for less than 40 of repondents to use the work/rest 50/10.

5. To summarize the results of the previous 4 points, there is major agreement to use the work/rest ratio 50/10 for both heat indices under the work rate groups resting and moderate and 40/10 for both heat indices under the work rate groups high and very high. This is an indication that as long as the work rate is increased, so more rest the body should take.

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Heat index (39°C-53°C)

1. Resting (work with hands only)

95 of the respondents agreed to use the work/rest 30/10 while 65 of the respondents agreed to use the work/rest 45/15.

2. Moderate (work with arms and hands):

88 of the respondents agreed to use the work/rest 30/10 while 72 of the respondents agreed to use the work/rest 45/15.

3. High (intense arms and trunks work):

111 of the respondents agreed to use the work/rest 30/10 while 48 of the respondents agreed to use the work/rest 45/15.

4. Very high (work activity cannot be sustained for long periods)

116 of the respondents agreed to use the work/rest 30/10 while 40 of the respondents agreed to use the work/rest 45/15.

5. To summarize the results of the previous 4 points, generally, there is significant agreement to use the 30/10 ratio with more assurance for high and very high work rate because the result show that the responses increased for the case of high and very high. Also, it is clear that there is a decrease for the work/rest 45/15 for the work rate high and very high. This is an indication that working 30 minutes and having a rest of 10 minutes is more preferable than working 40 minutes and having a rest of 15 minutes.

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Heat index (>54 °C)

1. Resting (work with hands only)

42 of the respondents agreed to use the work/rest 20/10, 42 of the respondents agreed to use the work/rest 45/15, 9 of the respondents agreed to use the work/rest 20/40, 70 of the respondents agreed to use the work/rest stop work.

2. Moderate (work with arms and hands)

39 of the respondents agreed to use the work/rest 20/10, 33 of the respondents agreed to use the work/rest 45/15, 20 of the respondents agreed to use the work/rest 20/40, 69 of the respondents agreed to use the work/rest stop work.

3. High (intense arms and trunks work)

23 of the respondents agreed to use the work/rest 20/10, 18 of the respondents agreed to use the work/rest 45/15, 32 of the respondents agreed to use the work/rest 20/40, 90 of the respondents agreed to use the work/rest (stop work).

4. Very high (work activity cannot be sustained for long periods)

20 of the respondents agreed to use the work/rest (20/10), 12 of the respondents agreed to use the work/rest 45/15, 25 of the respondents agreed to use the work/rest 20/40, 108 of the respondents agreed to use the work/rest (stop work).

5. To summarize the results of the previous 4 points, there is major agreement to stop the work for the heat index period >54 °C. However, there is slight indication that when the work rate is resting or moderate, so we can use the work/rest 20/10 and 45/15. Also, there is indication that if the work could continuous when the heat index > 54, so it would be better to work 20 minutes and having a rest of 40 minutes for the work rate high and very high.

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