A sweat stimulation system comprising: a mobile, wearable apparatus comprising a chamber sized to fit around a body part of a subject and to stimulate sweat loss in the subject, wherein at least a portion of the chamber provides a clear volume of air between the body part and one or more walls of the chamber upon receipt of air flow and subsequent expansion of the chamber, the chamber comprising an inlet and an outlet and the chamber being configured such that an air flow passes through the chamber from the inlet to the outlet to thereby create a controlled environment around the body part of the subject for stimulating sweat loss in the subject; characterised in that it comprises first and second relative humidity and temperature sensors, wherein the first relative humidity and temperature sensor is operably located at the inlet and the second relative humidity and temperature sensor is operably located proximate the outlet; an air fan and heat source coupled to the chamber and a flow meter associated with at least the air fan; and a controller communicatively coupled with at least the air fan, the heat source, the first and second relative humidity and temperature sensors and configured to monitor and control conditions of the controlled environment around the body part of the subject based, at least in part, on data received from the first and second relatively humidity and temperature sensors, the controller being configured to control and adjust inflow air temperature and/or air flow rate into the chamber so as to maintain a temperature of the environment within the chamber between 32°C and 50°C, maintain a relative humidity of the environment within the chamber at less than 50%, and maintain an air flow rate of between 0.2 cubic meters per minute and 4 cubic meters per minute. a mobile, wearable apparatus comprising a chamber sized to fit around a body part of a subject and to stimulate sweat loss in the subject, wherein at least a portion of the chamber provides a clear volume of air between the body part and one or more walls of the chamber upon receipt of air flow and subsequent expansion of the chamber, the chamber comprising an inlet and an outlet and the chamber being configured such that an air flow passes through the chamber from the inlet to the outlet to thereby create a controlled environment around the body part of the subject for stimulating sweat loss in the subject; characterised in that it comprises first and second relative humidity and temperature sensors, wherein the first relative humidity and temperature sensor is operably located at the inlet and the second relative humidity and temperature sensor is operably located proximate the outlet; an air fan and heat source coupled to the chamber and a flow meter associated with at least the air fan; and a controller communicatively coupled with at least the air fan, the heat source, the first and second relative humidity and temperature sensors and configured to monitor and control conditions of the controlled environment around the body part of the subject based, at least in part, on data received from the first and second relatively humidity and temperature sensors, the controller being configured to control and adjust inflow air temperature and/or air flow rate into the chamber so as to maintain a temperature of the environment within the chamber between 32°C and 50°C, maintain a relative humidity of the environment within the chamber at less than 50%, and maintain an air flow rate of between 0.2 cubic meters per minute and 4 cubic meters per minute.