This study investigates the effect of the dibutylphthalate spillage scenarios on the general layout of a plant using this auxiliary. The aim is to reveal the operating conditions of two alternative chambers with 300 and 900 m(3) volumes in a plant where possible dibutylphthalate addition to the processes can take place. The allocation of chambers and the related air exchange requirements are simulated to get rid of the negative impacts of possible spillages on the health of the workers. US EPA Indoor Air Quality and Inhalation Exposure (IAQX) Version 1.0 Model for single component solvent is used. The spillage of 5, 8 and 10 liters of di-butylphthalate within alternative production chambers are simulated by using 3 different air exchange rates (AER) 1 per hour (8 times in 8 hours), 5 per hour and 10 per hour. The simulations are performed by assuming immediate cleaning within half an hour after the spillage. The results showed that when 300 m(3) chamber will be used for di-butylphthalate addition to the processes, an air exchange rate of 10 per hour is required. In this chamber the air exchange rate can be reduced to 5 per hour only if not more than 5 liters of di-butylphthalate is applied at a time. On the other hand an air exchange rate of at least 1 per hour must be adopted to tackle the problem of 8 liter dibutylphthalate spillage in the room with 900 m(3) volume. However, an air exchange rate of 10 per hour is required for 10 liter di-butylphthalate spillages in this room.