**1. Introduction**

Climate change has been one of the most urgent problems to confront in the 21st century. The fifth report of the Intergovernmental Panel on Climate Change (IPCC) confirms that human influence on the climate system is clear and growing, with impacts observed across all continents and oceans [1]. Climate change has been degrading the quality of life for every creature on Earth. Glaciers have shrunk, ice on rivers and lakes is breaking up earlier, plant and animal ranges have shifted and trees are flowering sooner [2].

From the United Nations World Urbanization Prospects in 2017, 4.1 billion people were living in urban areas [3]. This means over half of the world (56% in 2020) live in urban settings. Urbanization is happening rapidly and it also accounts for global climate change. The rapid and large-scale urbanization leads to severe land-use conversion and impacts ecosystem services [4]. The latter refer to the direct and indirect contributions of ecosystems to human well-being. With ecosystems being damaged, human well-being is also affected. In the context of this pressing problem, urban microclimate studies have been gaining prominence due to rapid urbanization [5].

A microclimate is a small area within the surrounding larger area with a different climate [6]. Any given climatic region therefore comprises many other types of microclimates, which vary in characteristics from the region as a whole. Because our planet in general is broadly conducive to life, we – as humans – have populated its land masses. Comparing the human scale to that of the various habitats in which we live, the difference of these scales means that changes in the climates of these habitats may disproportionately affect the conduct of our daily activities.

That is the reason why the authors felt compelled to explore the relationships between microclimate and our physical and mental well-being. It is self-evident that climate change has various effects on the well-being of a person. As human beings we are conscious and aware of our surroundings, and our responses to changes in microclimate may affect our emotions. To elaborate, climate change might precipitate changes to micro-climates to the extent that for those inhabiting these biomes, the changes might be detrimental to physical and mental well-being. For instance, a study by Liu et al. [7] concluded that "the increasing research interest in thermal comfort and health has heightened the need to figure out how the human body responds, both psychologically and physiologically, to different microclimates".

This chapter reports a study conducted by students as an independent research project under the mentorship of a Research Scientist at the National Institute of Education, Singapore. In the Life2 Well Project (Learning at the intersection of AI, physiology, EEG, our environment and well-being) identical units of a wearable device containing environmental sensors (such as ambient temperature, air pressure, infrared radiation and relative humidity) were designed and worn respectively by five adolescents from July to December 2021. Over the same period, data from these sensors was complemented by that obtained from smart-watches (namely blood oxygen saturation, heart rate and its variability, body temperature, respiration rate and sleep score).

Among others, our work was inspired by earlier work of [8], in which they concluded that modified urban microclimates have a deep impact on the comfort of inhabitants. Palme and Salvati lamented that while there have been various studies conducted on the effects of urbanization on microclimate and how microclimate has changed human health in efforts to redesign and restructure urban areas., there have been relatively fewer studies on the relationships between microclimate and human health and emotions.

We see one of the potential contributions of our work to be our use of selfdesigned, low-cost, wearable units for measuring microclimate. The relatively low cost of these wearables has positive implications on the affordance of scalability,

and – consequently – on crowd-sourced citizen science in this as yet under-reported field of the relationships between microclimate and well-being.
