Wet-bulb globe temperature index estimation using meteorological data from São Paulo State, Brazil

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 São 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.

Maximum wet‐bulb globe temperature mapping in central–south Brazil: a numerical study

“…Many indices have been used to investigate thermal comfort in outdoor areas (Matzarakis and Mayer, 1997;Gómez et al, 2004;Emmanuel, 2005;Andrade and Alcoforado, 2008;Lai et al, 2014;Hirashima et al, 2016). The wet-bulb globe temperature (WBGT), which uses meteorological data in its estimates, has been widely used by many authors to assess occupational exposure to extreme heat in outdoor working sites (Dernedde and Gilbert, 1991;Bernard and Pourmoghani, 1999;Hunter and Minyard, 2000;Tonouchi et al, 2006;Liljegren et al, 2008;Gaspar and Quintela, 2009; Australian Bureau of Meteorology, 2013; Maia et al, 2015). Some authors have used numerical simulations to analyse the WBGT, or other indices, in order to help mitigate the effects of heat exposure (Bernard and Hanna, 1988;Kusaka et al, 2012;Kjellstrom et al, 2013;Kikumoto et al, 2016;Ohashia et al, 2016;Zheng et al, 2016).…”

Offering a model for estimating black globe temperature according to meteorological measurements

“…Maia et al . () measured the WBGT index using meteorological data in Brazil and found that the correlation between the estimated and actual values was about 0.77. In the present study, the correlation co‐efficient between the calculated and estimated black globe temperature was 0.952, which indicates that the model is appropriate to estimate the black globe temperature.…”

Risco de exposição à sobrecarga térmica para trabalhadores da cultura de cana-de-açúcar no Estado de São Paulo, Brasil

“…Neste estudo, utiliza-se o método proposto recentemente por Maia et al 48 , o qual utilizou dados meteorológicos observados no Estado de São Paulo para o seu desenvolvimento. A formulação é baseada no método proposto por Hunter & Minyard 41 .…”

“…A formulação é baseada no método proposto por Hunter & Minyard 41 . Uma das principais adequações apresentadas por Maia et al 48 foi a consideração de variação da fração de radiação direta do sol (f db ) e da fração de radiação difusa (f dif ), parâmetros considerados constantes por Hunter & Minyard 41 . Segundo Maia et al 48 , essa consideração garante uma maior precisão na estimativa do IBUTG, pois contabiliza os efeitos da nebulosidade, situação que comumente ocorre em dias quentes no Estado de São Paulo.…”

“…Os procedimentos para obtenção de f db e f dif , assim como todos os demais detalhes para a estimativa do IBUTG utilizada neste trabalho, podem ser encontrados em Maia et al 48 . Todos os cálculos para estimativa do IBUTG são realizados por meio de um software operacionalizado no Centro A matriz de IBUTG foi construída com pontos de latitude e longitude igualmente espaçados a cada 40km.…”