Pharmaceutically engineered aerosols (e.g. submicrometer and nano-particles and droplets) containing a hygroscopic growth excipient or agent are employed to improve the delivery of respiratory aerosols to the lung. Inclusion of the hygroscopic agent results in near zero depositional loss in the nose-mouth-throat regions and near 100% deposition of the aerosol in the lung. Targeting of the aerosol to specific lung depths is also possible. In addition, methods and apparatuses for delivering aerosols to the lung are provided. The aerosol is delivered to one nostril of a patient while a relatively high humidity gaseous carrier is delivered to the other nostril, resulting in post-nasopharyngeal growth of the aerosol to a size that promotes deposition in the lung.