The Heat Index (HI) in the city of Fortaleza, Ceará

Over time, changes in space have resulted in changes in natural characteristics. In this context, thermal comfort indicators have emerged, as developed to interpret environmental conditions in relation to thermal stress. The objective of this study was to apply the Heat Index (HI) in different neighborhoods of the city of Fortaleza, which choice was based on the different types of land cover. We carried out data collection campaign at ten points in the city, using thermohygrometer sensors. We applied the HI equation to the data collected, according to the intervals of the National Weather Service and the intervals adapted for the municipality. The data indicate that Fortaleza experienced high temperatures throughout the analyzed period (dry and hot months), having a negative impact on the HI (up to 42°C). The comparison of the comfort indicator classes showed that, in the original interval, few records indicated comfortable conditions in the different neighborhoods, while the interval of classes considering the acclimatization of the population indicated situations that were more comfortable. The worst comfort conditions occurred in the afternoon, between 12 p.m. and 2 p.m. The most critical points are associated with the density of buildings and the lack of urban green infrastructure, with neighborhoods Parque do Cocó and Bairro de Fátima (with more trees) that presented the highest frequency in the comfort class. We concluded that the entire territory of the city faces thermal stress; however, green structures have the potential to mitigate the adverse effects of the thermal field, improving human comfort in the urban environment.