A system and method for the monitoring of ammonia in a fluid. The ammonia monitoring system includes an ammonia sensor that is configured to detect trace amounts of ammonia (NH3) in a fluid (i.e., gas or liquid) that is pumped through it in real time. The real time ammonia sensor includes an interferometer configured to track the amount of ammonia that is pumped into the real time ammonia sensor. The ammonia monitoring system, via the real time ammonia sensor, is further configured to detect ammonia levels in industrial poultry houses and provide electronic feedback to the building's ventilation control system.