Population exposure to nitrogen dioxide (NO2) in the air results from emissions of nitrogen oxides in diverse combustion processes, in particular from vehicle engines. Studies conducted in the recent decade indicate that both shortand long‑term exposure to air pollution containing NO2 in concentrations close, or even lower than, currently binding norms is associated with increased mortality and more frequent hospital admissions. It is probable, that NO2 exposure contributes to asthma development, and clinical studies allowed concluding that increased NO2 exposure is a cause of asthma exacerbations. Prevention of these significant health effects requires lowering of population exposure to air pollution from road transport. It is feasible mainly through reduction of road traffic in densely populated urban areas. Changing from cars to public transport, cycling and walking would also contribute to an increase of physical activity, being an important issue in chronic non‑communicable disease prevention.