Improved Heat-Stress Algorithm

Next, the moderate solar radiation assumption had to be addressed and was corrected by a similar process as that for the wind. Since at noon the solar radiation was the highest, the adjustments began there. The approximation algorithm produced reasonable values during the hours when the Sun was at its peak, but there were large overestimates in the morning and at night. To correct this, the differences between the actual and estimated WBGT were compared to solar radiation measurements. The results from this were again used to create another correction curve. The difference between actual and calculated WBGT was reduced from approximately 2.0° to about 1.5° on the average. Combining the two curves improved the estimation significantly better than 0.5° on the average for the 40 days.

By using these improvements, a more realistic WBGT estimation value can now be produced. A variety of advantages come as a result of this. One of the most useful advantages is that a Web-based system can now be developed to automate and archive these calculations at a high update rate so that data are available everywhere for everyone. This Web automation system, in turn, will save meteorologists and safety personnel a considerable amount of time because they will no longer have to periodically record and archive WBGT measurements throughout the workday. Not only will the new algorithm help free up personnel but it will also make the thermal environment monitoring systems available to obtain site-specific WBGT data. This is extremely useful for researchers and other employees who are working on outdoor projects that are distant from the areas that the Web system monitors. Most importantly, the improved WBGT estimations will make outdoor work sites safer by reducing the likelihood of heat stress.

This work was done by Edward H Teets, Jr., of Dryden Flight Research Center and Steven Frehn of Highland High School (Palmdale, CA). For more information, download the Technical Support Package (free white paper) at www.techbriefs.com/tsp under the Information Sciences category. DRC-05-01