2D cells and 3D Test Systems can be exposed using “conventional” means, novel dispensing technology, or aerosolized materials. Traditional exposures are conducted using Test Articles solubilized or suspended in culture medium or physiological buffer. Digital dispensing can be used to expose our respiratory models by using the HP 300 dispenser that delivers ultralow volume droplets or patterns of DMSO-based materials into multi-well plates or onto the apical surface of tissues. The most physiological-like exposures are conducted using aqueous-solubilized materials and nebulized into small droplets (~2-10 microns), or using a smoking robot to deliver precisely controlled “puffs” of materials into tissue inserts containing test systems.