Interconnectivity between Web systems and sensor networks is used to provide smart services for the Internet of Things. These services are based on data collection and processing to obtain useful information about the supervised environment. With this information it is possible to provide smart services, but some of them must be considered as protected by the legislation regarding privacy of personal data. In order to face this issue, security and privacy mechanisms must be used. So as to deal with the limited resources in sensor networks, these mechanisms must be as lightweight as possible to preserve the enough Quality of Service. However, these mechanisms must fulfill security and privacy requirements defined by the regulations. This paper describes a Wireless Body Area Network application providing services to protect firefighter work in hazardous environments. The firefighter wears a special shirt with sensors embedded. These sensors are able to monitor not only the firefighter health status, but also they can be connected to external sensors in order to monitor the health status of the victims. These external sensors are part of the equipment carried by the firefighter to face the emergencies and save lives. Thus, they are able to obtain external medical aid.