Chronic obstructive pulmonary disease and asthma impose a substantial burden of disease. This narrative review focuses on potential population-wide interventions that are likely to have an impact on these diseases. The developmental origins of adult disease commence in utero, with maternal nutrition being of particular interest. However, to date, trials of maternal allergen avoidance, dietary supplementation or probiotics have not shown consistent protective effects against asthma. Poor indoor air quality, especially from biomass fuels as well as second-hand tobacco smoke, is a well-recognised risk factor for chronic respiratory diseases. This can be modified by cleaner fuels, cooking stoves or heaters, and improved ventilation. Although allergens are a risk factor for childhood asthma, the results of interventions to reduce exposures have been disappointing. Traffic-related air pollution is associated with an increased incidence of asthma in children. Primary prevention of the adverse effects of air pollution has focused on the development of ambient air quality guidelines, but enforcement remains a challenge in many countries. Occupational asthma may be induced by sensitisers or irritants in the workplace. Prevention involves eliminating the agent or reducing exposure as far as possible, which is more effective than respiratory protective equipment. Smoking cessation remains a key proven preventive strategy for chronic respiratory diseases. There is now an international framework for tobacco control, and recent innovations include plain packaging of tobacco. Chronic respiratory diseases can be substantially prevented by the above population-wide interventions.