<qa>  How long will the first determination of substances concentration and convenience grade of the other application be achieved?On the first appointment recruitment investigations will take place. After the person is enrolled to the study, the first determination of substances concentration in exhaled air and the convenience grade of the application form being exposed to will be achieved study day 1. After a 7 days lasting washout phase on study day 2 newly determination of substances concentration and convenience grade of the other application will be assessed. Each study day will have an approximate duration of 11 h. During this time 9 samples of the persons exhaled air will be collected. 