This systematic review assesses human inhalation exposure to microplastics (MPs) and nanoplastics in indoor and outdoor air, identifying data gaps and a framework for quantifying exposure. The study analyzed peer-reviewed articles, non-published papers, and grey literature to determine MP concentrations in air and their toxicological doses. Inhalation exposure doses were calculated using environmental data and toxicology studies, considering age groups and sampling locations. Results showed that indoor inhalation exposure was higher than outdoor, with infants having the highest exposure doses. Toxicology studies produced higher exposure estimates than environmental samples. The study highlights the need for standardized methods to measure MPs in air and evaluate human exposure, as well as the importance of considering particle size, sampling methods, and location in exposure assessments. Data gaps include the limited ability of current sampling methods to capture smaller MPs and the lack of universal standards for MP research. The findings suggest that MPs are prevalent in air, with higher concentrations in indoor environments, and that exposure varies by age and location. The study provides a framework for future research on MP inhalation exposure and health impacts.This systematic review assesses human inhalation exposure to microplastics (MPs) and nanoplastics in indoor and outdoor air, identifying data gaps and a framework for quantifying exposure. The study analyzed peer-reviewed articles, non-published papers, and grey literature to determine MP concentrations in air and their toxicological doses. Inhalation exposure doses were calculated using environmental data and toxicology studies, considering age groups and sampling locations. Results showed that indoor inhalation exposure was higher than outdoor, with infants having the highest exposure doses. Toxicology studies produced higher exposure estimates than environmental samples. The study highlights the need for standardized methods to measure MPs in air and evaluate human exposure, as well as the importance of considering particle size, sampling methods, and location in exposure assessments. Data gaps include the limited ability of current sampling methods to capture smaller MPs and the lack of universal standards for MP research. The findings suggest that MPs are prevalent in air, with higher concentrations in indoor environments, and that exposure varies by age and location. The study provides a framework for future research on MP inhalation exposure and health impacts.