What are the dangers associated with an exposure to ammonia?

How much, how long. With any chemical exposure, the affects depend on the route of exposure (contact, ingestion, breathing, etc), the concentration of the substance and the time of the exposure. In the case of ammonia, it can damage the skin, eyes, respiratory tract, etc in ways ranging from severe thermal and chemical burns to frost bite. http://emedicine.medscape.com/article/820298-overview.