Heat Stress in Night Clubs by Marc McNeill, Dept. Of Human Sciences, Loughborough University, Leics. LE11 3TU
Since 1988 there have been approximately 16 fatalities in night-clubs. Whilst drugs were often implicated, in most instances heat-stoke was the actual cause of death. It is likely that there are many less serious heat related problems. This report presents an investigation into night-club thermal environments. It considers the human behavioural, physiological and subjective responses. The investigation was composed of five parts:
Firstly a survey of night-club behaviour, attitudes and opinions on night-club thermal conditions was undertaken. A questionnaire was distributed on the Internet, to regular club-goers and people outside night-clubs. It resulted in 54 responses. Night-clubs were considered to be hot or very hot places where 61% of people would prefer to be cooler. 76% of the respondents had taken drugs. Soft drinks, rather than alcohol were usually consumed, however their consumption was often limited by high priced bottled water and disconnected free water supplies. 88% had experienced heat related illnesses.
The survey was followed by a thermal assessment of a night-club. The thermal conditions in the Loughborough Students Union auditorium were measured. A hand held humidity/temperature probe was used to assess the thermal conditions at chest height. It was found to have a maximum air temperature of 29oC with 90% relative humidity. A longitudinal study measuring air temperature and radiant temperature in the lighting rig found similar air and radiant temperatures and a maximum humidity of 70%.
The thermal conditions found in the night-club were simulated in a thermal chamber. Four male and four female subjects danced for one hour to two different styles of music and their physiological and subjective responses were quantified. Physiological measurements including core (aural) and mean skin temperatures, metabolic rate and sweat loss were taken. The results showed a rise in core (2.3°C) and skin (1.34°C) temperatures and a sweat rate of almost 1l/h. Subjects generally felt hot and sticky, preferring to be cooler. Comfort did not appear to be a significant factor. The extent to which music was enjoyed rather than its tempo appeared to affect the metabolic rate.
The results of the night-club simulation were compared with predictions from ISO7933 and the 2-node model of human thermoregulation (Parsons 1993). The models were found to be a fair approximation of the night-club thermal environments. The effects of a four hour exposure were then predicted. The 2-node model predicted a core body temperature increase to 39.07oC. This is well above the WHO limit of 38oC in occupational settings. Using ISO 7933 appropriate work-rest for dancing and water requirements were suggested.
The report concluded that there are significant risks of heat strain in night-clubs. Recommendations included "chillout" rooms to cool down between dancing, compulsory provision of free water, increase air velocity in night-clubs, and education on the risks of heat strain.