At the first sanitary conference, countries are urged to adopt measures to dispose of garbage and other wastes to prevent the spread of diseases, and the Bureau is instructed to elicit from the countries information regarding the sanitary conditions of their ports and territories and to encourage or enforce seaport sanitation, including sanitary improvement of harbors, sewage disposal, soil drainage, street paving, and elimination of the sources of infection from buildings. In 1929, the pages of the Boletín de la Oficina Sanitaria Panamericana admonish that: "Without knowledge of hygiene and sanitation and without the means of applying that knowledge, protection of the public's health is reduced to a mere myth."

Reflecting the social situation at mid-century, the 1950-1953 edition of Health Conditions in the Americas notes that: "Since the countries and territories of the Americas are essentially rural ... there are increasing needs and opportunities for promotion by health services of satisfactory water supplies and safe disposal of sewage in rural areas." Nevertheless, toward the end of the 1950s, less than 60% of people living in urban areas have access to water services and less than 8% in rural areas do; sewerage is available to only 28% of those living in cities and to practically no one in rural areas.

In 1967 the Organization establishes the Pan American Center for Sanitary Engineering and Environmental Sciences in Lima to address regional environmental health concerns. A decade later, member countries request the Director to set up a disaster unit to define the policy of the Organization, formulate a plan of action for various types of disasters, make an inventory of available resources, and train the necessary personnel.

Environmental concerns expand beyond the traditional focus on water supply and sanitation. By the late 1980s, then director Dr. Carlyle Guerra de Macedo draws an association between industrial development and environmental deterioration: "Air, water, and soil pollution and the exposure to toxic substances are the principal environmental health risk factors associated with development."

Today, in large measure thanks to the work of the Organization with its member countries, good progress has been made in extending coverage of water supply and sanitation, improving the quality of the environment, protecting workers' health, and reducing the vulnerability of countries in the face of disasters.