In this study, the area of a biofilter representing an active area source was sampled by taking 12 odour samples from the gaseous effluent and measuring the physical parameters of the source, so that we can obtain the odour emission rate (OER) specific to the source. The odour sampling process is a crucial step in the assessment and monitoring of odour pollution. Direct measurement of odour concentration in the ambient air is often not sufficient to determine whether an activity is responsible for producing olfactory discomfort to the receptors. To observe the contribution of the source to olfactory pollution and air quality by estimating the odour concentration in the ambient air, the odour emission rate (OER) was taken into account, which is expressed in odour units per second (ouE/s) and is obtained as the product of the odour concentration and the airflow rate associated with the source. The odour emission rate was entered into the dispersion program AERMOD for mathematical modeling. In order to estimate the odour concentration in the surrounding air in the adjacent areas to the sampled biofilter, 2 mathematical models were made to illustrate the odour concentration on the site and in its vicinity in the most unfavorable weather conditions „Highest values” and „98th Percentile” to illustrate the concentration in the surrounding air excluding the 2% unfavorable weather condition