The medical community throughout most of the 19th century blamed 3 potential causes for all diseases: 1) contagion by direct contact with sick persons, thus justifying quarantine measures; 2) the epidemic constitution of the atmosphere-diseases were blamed on the changing weather or seasons; 3) the most widely accepted view which was the miasmatic theory which claimed that diseases were caused by bad odors in the air created by decaying animal and vegetable matter, stagnant water and swamps, and general public squalor. Pubic health reformers accepting this last theory championed the need for environmental cleanup through sewage and refuse removal, pure water, and better ventilation in buildings, all of which became major 19th century public health crusades.