## 1 Introduction  
According to the World Health Organization (WHO), chronic diseases such as chronic obstructive pulmonary disease (COPD) will become the third-main cause of death worldwide by 2020 [1]. The environment (e.g., gases, sound level, and ultraviolet radiation), the patient's behavior (e.g., activity), and the physiological state of the subject (e.g., vital signs) are important factors of disease development. Furthermore, the simultaneous monitoring of these domains has great importance in the safety monitoring of workplaces. Under the rapid development of technologies, the world has entered into a new era of interconnected networks via the Internet of Things (IoT) as one of the most powerful communication paradigm [2]. The IoT supports the connection of objects putting forward technologies and networking architectures. Numerous objects in houses or vehicles are connected and share information and resources. Therefore, IoT has become a key component in healthcare applications and environmental monitoring [3]. Wireless sensors can also measure environmental conditions and parameters related to the health status [4]. Continuous health monitoring is available and with the methodology of mobile health (mHealth) or electronic health (eHealth), the medical paradigm shifts from diagnostics and treatment towards predictive, preventive, personalized, and participatory (P4) medicine [5; 6; 7]. In contrast to reactive traditional medicine, P4 medicine is proactively seeking causes rather than symptoms of diseases. It addresses patients, consumers, and physicians. Personalized medicine motivates actively participating lifestyle observation, leading to improved quality of life. Studies have shown that wearable technology has many advantages and benefits in healthcare [8; 9]. Wearable sensors gained attention of researchers, vendors, and consumers [10; 11; 12]. Based on wearable devices and their advantages in healthcare, the medical IoT (mIoT) is the most acceptable solution reaching proactive and personalized medicine [13; 14]. Miniaturization and user convenience boosted mass production of non-invasive sensors with the applications in well-being, lifestyle, and personalized healthcare [15; 16]. Wireless body area networks (WBAN) are widely used to combine wearables for measuring physiological parameters such as the heart rate (HR), respiration rate (RR), electrocardiography (ECG), body temperature, and blood pressure (BP). WBAN is also applied to measure physical activities (e.g., body positioning, motion tracking) and environmental conditions. Such applications are of great importance for chronic disease management (e.g., COPD) and safety of workplace monitoring (e.g., workers on construction sites). Then health and safety (H&S) are interwoven domains [17; 18]. Several publications reported the influence of air pollutants including carbon monoxide (CO), nitric dioxide (NO\({}_{2}\)), and particle matter (PM\({}_{2.5}\) and PM\({}_{10}\)) [19; 20] on health. However, such ambient parameters are not limited to hazardous gases. The loudness of environmental sound is important, too. Long-term exposure yields hearing loss or psychological impairments [21]. Overex to ultraviolet (UV) radiation causes skin cancer, eye irritation, and aging skin [22]. Furthermore, air temperature, humidity, and air pressure are usually delivered by wearables (Table 1). Skin temperature and photoplethysmography (PPG) are the commonly monitored physiological signals [23]. Long-term and continuous monitoring of safety conditions with respect to a combination of (i) environmental conditions, (ii) behavioural parameters, and vital signs can significantly contribute protecting health in hazardous situations by early warning systems [24]. Nevertheless, there is lack of efficient wearable systems to monitor environmental, behavioral, and physiological parameters at the same time [2].