Contents lists available at ScienceDirect Urban Climate journal homepage: www.elsevier.com/locate/uclim A new outdoor environmental heat index (OEHI) as a simple and applicable heat stress index for evaluation of outdoor workers Farideh Golbabaei a , Hamidreza Heidari b, ⁎ , Aliakbar Shamsipour c , Abbas Rahimi Forushani d , Abbasali Gaeini e a Dept. Occupational health, School of Public Health, Tehran University of Medical Sciences, Tehran, Iran b Dept. Occupational health, School of Public Health, Qom University of Medical Sciences, Qom, Iran c Dept. Physical Geography, School of Geography, University of Tehran, Tehran, Iran d Dept. Epidemiology and Biostatistics, School of Public Health, Tehran University of Medical Sciences, Tehran, Iran e Dept. Sport Physiology, School of Physical Education and Sport Science, University of Tehran, Tehran, Iran ARTICLE INFO Keywords: Outdoor environment Heat index Tympanic temperature ABSTRACT Several indices were introduced for assessment of heat stress worldwide many of which devel- oped in the North American or European countries and may encounter some restrictions when utilized in countries with different climates such as developing countries. Moreover, only a few of them can demonstrate the actual thermal condition, comprehensively. Accordingly, the main purpose of this study was to develop an Outdoor Environmental Heat Index (OEHI), which not only to be able to cover the important personal and environmental parameters affecting to heat stress and well correspond to created heat strain, but also can be used generally wherever of the Iran country and other countries with similar climates. The final presented index, OEHI, was modeled based on air temperature and air enthalpy. These parameters are part of the common metrological data reported daily by each weather station, so the index can be easily reported daily for public awareness of heat situation. 1. Introduction Over the previous decades a variety of validated and standard indices have been introduced as protective measures to mitigate the heat stress consequences (Crowe et al., 2009; Roshan et al., 2019). Since many of these indices, such as Standard, I.S.O, 1989 (Wet Bulb Globe Temperature Index, WBGT) and Standard, I.S.O, 2004c (predicted Heat Strain, PHS) have been developed based on European and north American subjects and climates (McNeill and Parsons, 1999) it is expected that they are primarily employed in those countries. There are a lot of concerns and questions when using thermal indices in conditions that are different from the original ones. For example, indicators introduced in developed countries can be used with the same precision in developing countries? Do they have similar applicability for indoors and outdoors? What influences may different climates have on performance of an index? Which parameters (personal or environmental or combination of them) must be integrated in an index to demonstrate thermal situation more accurately and realistically? Can demographic characteristics of a society affect the performance of thermal indicators? The studies showed that, in spite of the scope of the standards, which is international, little consideration has been made about how valid https://doi.org/10.1016/j.uclim.2019.100479 Received 5 February 2019; Received in revised form 7 April 2019; Accepted 13 May 2019 ⁎ Corresponding author. E-mail addresses: Fgolbabaei@sina.tums.ac.ir (F. Golbabaei), Hr-heidari@muq.ac.ir (H. Heidari), Shamsipr@ut.ac.ir (A. Shamsipour), Rahimifo@tums.ac.ir (A.R. Forushani), Aagaeini@ut.ac.ir (A. Gaeini). Urban Climate 29 (2019) 100479 2212-0955/ © 2019 Elsevier B.V. All rights reserved. T