Specific Enthalpy Based Heat Stress Index for Indoor Environments without Radiation Effect

Over 100 human thermal indices have been developed to predict the combined thermal impact on the body.In principle,these indices based on energy thermal budget equations should not only be the most complex but also be the most accurate.However,the simple indices based on algebraic or statistical models[e.g.,the wet-bulb globe temperature(WBGT)]continue to be the most popular.A new heat stress index,the enthalpy dry-bulb temperature(EnD)for indoor environments is developed and validated in this study.The EnD index is unique in that it uses the air specific enthalpy,not the wet-bulb temperature,to measure the latent heat transfer from the skin to the surrounding environment.Theoretically,the EnD index can be treated as the equivalent temperature based on the convective heat transfer coefficient h_(c).Comparison is made between the EnD index and the widely used WBGT index based on the experimental data taken from three independent studies available in the scientific literature.The results show that the EnD index can reduce the overestimation of the dry-bulb air temperature and thus reduce heat stress in most cases,especially for hot and humid environments.It can be concluded that the EnD index has the potential to replace the WBGT index as the standard heat stress index in the future.

The Epidemiology of Cardio-Vascular Diseases in Relation to the Air Quality of Abattoirs in Port Harcourt, Nigeria

This study investigated the spatial occurrence of cardiovascular diseases associated with the air quality of selected abattoirs in Port Harcourt. Using the simple random sampling technique, the Trans-Amadi, Rumuokoro, Rukpokwu and Elelenwo abattoirs were selected and used for the study. However, both gases and particulates matter which include NO2, SO2, H2S, CH4, CO, PM2.5, and PM10 were collected at distances of 0, 20, 50, 100, 200 m with the aid of a hand held multi-gas monitor. The questionnaire was used to obtain the demographic and socio-economic characteristics of the respondents, duration of job in years, as well as individual frequency of hospital visitation based on symptoms of cardiovascular diseases. The electrocardiogram was employed to diagnose manifestations of ischemic heart disease among the workers especially in the roasting section. Analysis of data collected was done using the Step-wise multiple regression technique. Result showed that occurrence of cardiovascular diseases is a function of pollutant concentration (CO - r = 0.57) at Rumuokoro abattoir;(O3 - r = 0.40, SO2 - r = 0.23, CO - r = 0.14) at Rukpokwu abattoir, duration of exposure (DOE - r = 0.22) at Rumuokoro abattoir, (DOE ? r = 0.40) at Trans-Amadi abattoir;and (DOE - r = 0.20) at Elelenwo abattoir;age of worker (r = 0.06) at Rukpokwu abattoir, (r = 0.30) at Elenlewo abattoir and daily duration on the job (JOBD - r = 0.13) at Elelenwo abattoir. Findings indicate that there is a positive correlation between occurrence of vascular diseases and pollutant concentration, duration of exposure, age and duration on the job but varies from location to location. Periodic epidemiological and air quality assessment of workers at the abattoirs are strongly advocated.

Human thermal comfort under lateral radiant asymmetries

Occupants’thermal comfort in buildings may be affected by the cool wall and warm wall,which is attributed to the effect of asymmetric radiation.However,the previous majority of the researches on asymmetric radiation were mainly about the comfort limits under thermally neutral condition within 1∼1.5 h but had not considered the effect of exposure duration and the condition beyond neutral.To investigate the human thermal comfort under an asymmetric environment caused by the cool wall and warm wall,forty-four subjects were exposed to neutral air temperature with lateral radiant asymmetries in winter and summer for 3 h.The results indicated that the cool wall caused thermal discomfort easier than the warm wall because the thermal sensation decreased and deviated from neutral with time.Subjects’sensitivity of local parts to asymmetric radiation was affected in the conditions beyond neutral,thus their acceptability to asymmetric radiation decreased.The currently used limits of radiant temperature asymmetry tended to underestimate the local discomfort due to the walls.For the conditions tested,The limits of 5%dissatisfaction in radiant temperature asymmetry were 4.4°C(180 min)and 1.8°C(60 min and 120 min)for the warm wall,and 1.8°C at 60 min for the cool wall.