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Int J Biometeorol (2015) 59:13951403 DOI 10.1007/s00484-014-0949-7
ORIGINAL PAPER
Wet-bulb globe temperature index estimationusing meteorological data from So Paulo State, Brazil
Paulo Alves Maia & lvaro Czar Ruas &
Daniel Pires Bitencourt
Received: 3 May 2013 /Revised: 16 December 2014 /Accepted: 23 December 2014 /Published online: 30 January 2015 # ISB 2015
Abstract It is well known that excessive heat exposure causes heat disorders and can lead to death in some situations. Evaluation of heat stress on workers performing indoor and outdoor activities is, nowadays, conducted worldwide by wet-bulb globe temperature (WBGT) index, which calculation parameters are dry-bulb, natural wet-bulb, and globe temperatures, which must be measured at the same time and in location where the worker is conducting his/her activities. However, for some activities performed in large outdoor areas such as those of agricultural ones, it is not feasible to measure directly those temperatures in all work periods and locations where there are workers. Taking this into account, this work aims to introduce a WBGT index estimation using atmospheric variables observed by automatic meteorological stations. In order to support our estimation method, we used, as a test-bed, data recorded in the State of So Paulo (SP), Brazil. By adding the cloudiness factor in the calculation through measurement of solar radiation, the algorithm proved to be as efficient as those mentioned in this work. It was found that this method is viable, with WBGT-estimated values obtained from meteorological data measured by stations with a distance of less than 80 km. This estimate can be used for monitoring heat stress in real time as well as to investigate heat-related disorders and agricultural work.
Keywords Heatstress .Meteorologicaldata .Heatdisorders .
Outdoor activities
Introduction
In Brazil, outdoor workers are commonly exposed to extremely hot environments. In addition, in tropical and subtropical
countries, climate changes tend to increase human heat exposure in workplaces where there is no cooling systems (Hyatt et al. 2010). The heat exposure, added to a large production of internal heat due to heavy activities, causes a fast heat loss of the human body in order to achieve thermal balance. Heat stress occurs when the body is unable to cool itself enough to maintain a healthy temperature. This processwhich depends on the thermal load and the...