This document comments on document PPR 13/17/1 and highlights that development of guidelines for managing ammonia effluent generated from ammonia-fuelled ships must account not only for the acute and short-term toxicity of ammonia effluent, but also the wider impacts of reactive nitrogen release, including impacts to marine organisms from chronic, long-term ammonia effluent release, and disturbance to the nitrogen cycle. Prohibiting discharge of ammonia effluent to the marine environment is the management measure best aligned with the precautionary principle.