 Therefore, the equation in the previous section is correct in a strict mathematical sense, but it is a gross oversimplification of actual exposures, which are the sum of the integrals of all activities in all microenvironments.For example, the equation would have to be calculated with the specific concentration of a compound in the air in the room during the time interval.Similarly, the concentration in the ambient air would apply to the time that the person spends outdoors, whereas the concentration in the food that the person ingests would be added.