The longer an individual is exposed to a strong odor, the less aware of the odor the individual becomes. this phenomenon is known as

The longer an individual is exposed to a strong odor, the less aware of the odor the individual becomes. This phenomenon is known as sensory adaptation. 

Sensory adaptation is the ability for your sensory feelings to change and adapt based on their surroundings. One example is wax warmers in the house. I have a wax warmer burning constantly with a scent in 6 places of my house, the first day or so I can smell it but by the second/third day I can't. However, people coming into my house for the first time can smell how strong it is. In this case, my senses adapted to the smell in my house.