Limits of and possibilities to improve the IREQ cold stress model (ISO/TR 11079). A validation study in the field

Estimated insulation (I-cl) of clothing worn by workers daily exposed to ai r temperatures between 0 and 15 degrees C was compared with the correspondi ng insulation calculated for thermal neutrality using the IREQ-model (IREQ( neutral), ISO/TR 11079). The goal was to determine possible limitations of the applicability of the IREQ-model and to stress to necessities and possib ilities to improve the model. Sixteen female and 59 male workers (16-56 yr) were monitored during their work. According to their cold stress at the wo rkplace they were allocated to three groups (33 persons were exposed to con stant temperatures of more than 10 degrees C, 32 to less than 10 degrees C, and 10 persons experienced frequent temperature changes of 13 degrees C). Another categorization concerned workload (8 persons worked at metabolic ra tes of less than 100 W/m(2), 50 persons worked at 101-164 W/m(2), and 17 wo rked at more than 165 W/m(2), respectively). The analysis of the difference s between estimated worn insulation (I-cl) and calculated IREQ(neutral) rev ealed that the IREQ-model applies for air temperatures up to 15 degrees C a nd for temperature changes of 13 degrees C (at least) but needs to be impro ved with respect to gender. The IREQ model does not apply sufficiently for high and largely varying workloads (165 W/m(2) and more). However, these si tuations are beyond the currently available possibilities to protect worker s adequately with conventional clothing material. A suitable short-term mea sure is a more even work flow by avoiding activities with very high and low metabolic rates. (C) 2000 Elsevier Science Ltd. All rights reserved.