Container buildings used for residential and business purposes in Johannesburg, South Africa and potential heat-related health risks.

Background : Outdoor and indoor air temperature affects human health and wellbeing. Climate change projections suggest that global temperatures will continue to increase and this poses a threat to health. Housing that can protect humans from the adverse effects of temperature is essential, especially in the context of climate change. Method : In this cross-sectional study, we measured indoor temperature inside shipping containers comprising a seven-storey block of apartments and businesses in Johannesburg, South Africa. We assessed indoor temperature and relative humidity; evaluated measured temperatures in relation to thresholds known to be associated with adverse health risks; and sought to understand heat-health perceptions and symptoms of people living and working in shipping container units. Results : Median indoor apparent temperature (AT) (a combination of temperature and relative humidity) was 16 °C with values ranging from 6 °C (observed at 8:00) to 42 °C (observed at 17:00). Insulated units had temperatures between 2°C and 9°C cooler than uninsulated units. Heat-health risks from AT exposure were likely in all units, although there was variation in the number of occurrences that AT measurements exceeded the four symptom bands of caution, extreme caution, danger and extreme danger. Some participants believed that their units were hot during hot weather and most people opened windows or did nothing during hot weather. Few participants reported experiencing adverse heat-health impacts, except for experiencing headaches (n=62, 58%) and feeling tired or weak (40%). Conclusion : Container units should be insulated and have adequate windows for ventilation when used for residential and commercial purposes, especially in hot climates. Awareness regarding heat-health risks of living and working in hot spaces needs to be done, especially in the context of repurposed container units.