Investigation of temporal variation of human thermal discomfort in Djibouti

Abstract

Hot weather causes heat stress in dairy humans. Although effects are more severe in hot climates, dairy cattle in areas with relatively moderate climates also are exposed to periods of heat stress. The objective of the study was to determine the thermal comfort or discomfort of people to the prevailing environmental conditions particularly temperature and relative humidity during the various seasons of the year at Djibouti in terms of thermal discomfort index (DI). The DI was calculated from Thom’s formula The area of study is Djibouti, a small and hot country in the east of Africa. The data for the calculation have been taken from the readings of airt emperature and relative humidity throughout a period of 29 years (1985-2014) in the Djibouti Aerodrome station, Randa, Obock and Ali-Sabieh. A mass curve method was used for consistency and homogeneity of the data and for missing data, arithmetic methods was used. The main objective in this study is to make assessment on stress caused by temperature and humidity in order to establish the withal of Djibouti’s comfort levels during the various seasons of the year which can be useful in evaluating human discomfort and apply the index on a national level to determine which months possess the most extreme values. Thom’s Table of DI Ranges was used to determine the percentage of the population of Djibouti suffering from discomfort or otherwise. Times series analysis was done to determine the daily and seasonal discomfort level of the population. This study found that less than 50% of the population experienced the sense of discomfort during January February March April October November and December in the morning time and more than 50% of in the afternoon. But more than 50% of the population suffered from discomfort during May June July August and September in the morning time and almost all the population in the afternoon. The discomfort indices greater than 30 or 32 (indicating 100% of the population feeling discomfort or the condition of medical emergency, respectively) were not attained in Djibouti.