The Profertil plant in Bahia Blanca, Argentina is designed to produce 1.1 million tonnes of  urea and 775 thousand tonnes of ammonia annually (Profertil 2000). The start-up of the ammonia plant was completed in the first week of October 2000. In recent months, a number of releases of ammonia have occurred at the Profertil plant.
On August 28th, an ammonia leak occurred during start up procedures. The leak is believed to have been caused by excess pressure in a tank holding 200 cubic metres of aqueous ammonia. Measurements taken after the release showed levels of ammonia in the air of between 40 and 100 ppm. The maximum allowable concentration is 35ppm. Levels of ammonia in the air at the time of the release may have been considerably high than these levels, as discussed in Section 3.
People in the vicinity reported burning eyes and respiratory tract, and reported that it was “impossible to breathe”. More than 80 people were hospitalised, many requiring breathing assistance. Students at schools near to the industrial complex were evacuated. As a result of the release, the Argentinean regulatory agency Sectretaria de Polytica Ambiental (SPA) ordered the plant to stop production at the facility after August 31.
On November 8th, a leak of ammonia gas occurred during the start-up of the urea plant. The concentration of ammonia was measured at 4-12 ppm for less than one hour at the plant fence line. As a result of the release, the Argentinean regulatory agency Sectretaria de Polytica Ambiental (SPA) ordered the plant to stop production. The ammonia plant remained in operation.
This document covers the production and uses of ammonia and urea, including a discussion of accidental industrial releases of ammonia. The toxicology and legislation of these compounds are also discussed.

2000 Greenpeace Ammonia and Urea Production Incidents ammonia realease.pdf