Walkability and outdoor thermal comfort evaluation with a portable low-cost environmental monitoring platform

The interaction between walkability and outdoor thermal comfort (OTC) assessments is key in the context of climate change, since optimizations of outdoor areas are relevant to ensure overall cardiovascular health of the population (overheated urban environments discourage outdoor activities, resulting in increasingly sedentary, indoor lifestyles). Motivation of the study was to combine walkability and OTC assessments with guided walks using wearable equipment. 6 walks on different days were conducted in a subtropical location. Research participants completed the approximately 1km circuit in 40min, with five stops, during which they filled out a questionnaire that included items related to the accessibility of street segments, crossings and at a given stop, and OTC-related items. Concurrently, an Arduino-ESP32 platform built on a backpack registered air temperature and humidity, wind speed and globe temperature. Physiological data were also recorded (skin temperature and heart rate). A pairwise comparison of perceptual evaluation and physiological response tested the impact of metabolic activity rate of an active walker against a sedentary person, which remained seated on a wheelchair, both with equivalent BMI. Altogether 10 students comprise the sample. As per research protocol, at a pre-conditioning stage, participants remained 30min indoors in an air-conditioned thermal environment, leaving that space fitted with Thermochron iButtons and heart rate straps, accompanied by two researchers, one of which wore the portable monitoring unit and the other pushed the wheelchair. Exposure conditions during campaigns showed mild ambient temperatures, mostly under cloudy conditions. Sedentary subjects felt slightly cooler at the stops and less satisfied with the street segments than walkers in terms of OTC, with noticeable point-specific changes in perceptual responses. Accessibility of the segments was rated worse by sedentary subjects, and again differences in accessibility evaluation were point specific. Heart rate was higher for the walker whereas skin temperature showed minute effects from point exposure.