This concept paper concerns the guidance document on quality aspects of human medicinal products intended for delivery of drug substance into the lungs or to the nasal mucosa with the purpose of evoking local or systemic effect. These include pressurised metered dose inhalers, dry powder inhalers, products for nebulisation and non-pressurised metered dose inhalers as well as pressurised metered dose nasal sprays, nasal powders and nasal liquids.