The risk of heat stress to South African emergency medicine registrars rotating through hospitals in warmer climate zones during summer months

Most South African Medical registrar programmes involve rotation between a number of teaching hospitals within a geographic region. For some of these programmes this includes a short rotation to a more remote hospital, in some instances located in a different province of the country, and distinct climate zone. This is the case for the University of the Witwatersrand Emergency Medicine programme, based in Johannesburg, which includes a two month remote rotation through Klerksdorp, a city located in the North West Province, with a markedly warmer climate, particularly during the summer months. The difference in climatic conditions, short duration of the rotation, and the lack of a defined period for acclimatisation heightens the risk of heat stress to these rotating Emergency Medicine registrars, particularly in residential environments. This holds a range of secondary risks, relating to the level of focus, agitation, and impact on sleep between shifts. In this study we use a collection of 3229 temperature and humidity readings taken over the period of a month in early summer in Klerksdorp. Using Humidex, a thermal comfort index for occupational health and safety, we quantify the risks of heat stress to acclimatised and unacclimatised workers, and the times of day of greatest heat risk. These findings can provide valuable direction in the scheduling of rest periods, the allocation of longer and shorter shifts through the day, and the provision of infrastructural adaptation to heat stress such as water coolers and air conditioning.