**3.1 Collecting microclimate data**

To collect microclimate data, a small portable device that could be worn on the waist was designed in order to measure the following ambient environmental conditions:


In total, five such devices were built by the authorial team. Each device was worn by the first and second authors and by their adolescent peers. The devices measured 12 cm by 6 cm by 2 cm respectively, and contained a low-cost sensor for each of the preceding environmental variables listed, together with a battery with sufficient capacity to power the sensors over the course of a typical day. The device could be secured to a belt by two regular clothes clips.

Every 15 minutes, each device would automatically log its measurements in to a designated cloud-based spreadsheet. At the same time, the device would ping the nearest publicly-accessible weather station (as provided by the Singapore Meteorological Service) for the wind speed and wind direction prevailing at that time. **Figure 1** shows schematics of the components, and **Figure 2** shows an assembled device.
