Inhalation Exposure, Uptake, and Dose
Uptake of pollutants by the respiratory tract is sequential. Gaseous and particulate pollutants must first sorb or deposit onto the liquid surface of the lungs before they can travel through the liquid layer, come into contact with the lung tissue, and diffuse into the bloodstream. The fate and transport of pollutants that enter the respiratory system are dependent on many factors, including the diffusivity, solubility, reactivity, and size of the pollutants; the airflow characteristics in the respiratory system; and the physiology of the respiratory and vascular systems. Mathematical models can be used to estimate diffusion of pollutants from the respiratory tract to the bloodstream as well as partitioning of pollutants in the body after they have been absorbed.