In the domain of software development, agile techniques are increasingly being used to improve the development process. Agile software development relies in part on rapid feedback of working software products to validate user requirements. There has been some effort to introduce agility in security-critical systems, using an explicit representation of security concerns known as an iterative security architecture. We propose a similar explicit representation of safety concerns in order to introduce agility into the safety-critical development process: the agile health model.