evaluation of heat stress among farmers using environmenta l and biological monitoring: a study in north of iran

in this  cross sectional s tudy carried out in s pring and s ummer, 79 farmers  working  in different  job  pos itions including agriculture, hus bandry and horticulture in north of iran were participa ted. evaluation of the heat s tres s was conducted us ing wet bulb glob temperature (wbgt) index according iso7243 and heat s train evaluation us ing  meas uring  the  individual  phys iological  res pons es  including  aural,  oral  and  mean  s kin  temperatures according iso 9886. the demographic characteris tics of the s ubjects s uch as age, job experience, bmi and body area were als o gathered  through a ques tionnaire. in general, the s ubjects were in middle ages  (38.44±8.86 yr) and mean and s tandard deviation of years  of expe rience were almos t high (17.49±9.41 yr), too. the s tatis tical analys is was performed  by spss 18 s oftware. the  res ults  s howed that the wbgt index values  had  ranging from 24 to  32.6°c in  s ummer  regardles s  of clothing  ins ulation,  metabolic  rate  and  work  res t  regimens .  of cours e, by correction of thes e parameters the wbgt will accompany with an incens ement. convers ely, the heat s train monitoring revealed that in no cas e the aural and oral temperatures are higher than the limit allowed. the bes t correlation  coefficient  was obtained  for aural temperature  and wbgt index (r= 0.84, p< 0.001). it  s eems that evaluation of hot and humid environment us ing wbgt index can be as s ociated with an overes timation and encountered our judgment about the environmental condition with a s ignificant error.