International Standards for the Assessment of the Risk of Thermal Strain on Clothed Workers in Hot Environments: Comment

International Standards for the Assessment of the Risk of Thermal Strain on Clothed Workers in Hot Environments: Comment

Abstract

Downloaded from annhyg.oxfordjournals.org at Infovell on November 10, 2010 (a) p. 301: Ep ˆ Ereq a8 Ep ˆ Ereq and Swp ` Dmax a8 and Swp ` Dmax (b) p. 331: DLE1 ˆ DLE1 ˆ 60Qmax a…Ereq À Ep † 60Qmax aSwp (c) p.302: wp :wp Emax wp :wmax Item (a) in the table refers to the conditions permitting a full shift (8 hours') exposure: . . . . Ep = predicted evaporation rate WmÀ2 Ereq = required evaporation rate WmÀ2 Swp = predicted sweat rate WmÀ2 Dmax = maximum water loss, for example 1000 W.h mÀ2 or a 2.56 kg warning level for a non-acclimatized worker. Where DLE1 [allowed exposure time is 480 min (8 hours)], the heat stress is tolerable, the person is likely to be in thermal equilibrium or close to it, so the predicted evaporation rate equals the required evaporation rate. So Ep ˆ Ereq not Ereq a8 as per Parsons. Similarly, a tolerable heat-stress situation would Received 11 November 1999. 155 Letters to the Editor ISO (1989) Hot EnvironmentsÐAnalytical Determination and Interpretation of Thermal Stress using Calculation of Required Sweat Rate. ISO, Geneva. So it is obviously incorrect to compare (say) 0.5 with