Privacy appears as a major issue for pervasive computing applications. Several models have been proposed to address privacy challenges. Successful design requires awareness of the technology's users and that their desires and concerns are understood. This is difficult as few empirical researches exist about potential pervasive users that designers can use. Complicating design further is the fact that pervasive systems are typically embedded or invisible, making it difficult for users to know when these devices are present and collecting data. As users have a limited understanding of the technology several privacy, design, and safety issues are raised. This paper discusses how privacy might be preserved in a pervasive computing environment. It presents some research developments in these areas to address privacy concerns. Open issues and challenges are also examined.