Assessing seasonal variations in urban thermal comfort and potential health risks using Physiologically Equivalent Temperature: A case of Ibadan, Nigeria

Thermal environment can act both as constraint and resource to human being. This study analyzed the fundamental environmental factors that thermal environment depend upon with the aim of acquiring knowledge and creating awareness about the likely constraint that thermal environment might pose to human health in Nigeria using Ibadan as a case study. Physiologically equivalent temperature (PET), a thermal comfort index which is a product of the interactions between fundamental environmental factors was equally analyzed. Air temperature of 30 °C and below that accounted for about 33% of the total study period concentrated mainly within 2nd decadal-June and 1st decadal-October while relative humidity of 60% and below that accounted for about 11% occurred in the 1st decadal-January to 3rd decadal-March and in 2nd decadal-November to 3rd decadal-December. Only six classes of physiological stress levels ranged from slight cold stress (slightly cool) to extreme heat stress (very hot) were identified. The PET values of > 19 °C to 31 °C accounted for about 26% of the total period while PET values of > 31 °C to > 42 °C accounted for the remaining percent. Two shifts were noticed in the seasonal values of PET, first shift was around DM '12 (dry months-2012) and the second shift was around TDS '12 (transition to dry season-2012). The study concludes that both direct and indirect health effects of thermal environment may be growing in the study area in view of the findings presented. The findings of this study present important information that should encourage efforts to implement local and natural adaptation actions in Nigeria. The results are invaluable for policy-making decisions, especially for planning short- and long-term health intervention strategies aimed at preventing and minimizing the constraint pose by thermal environment to human health.