Dr. William Farr, the assistant commissioner for the 1851 London census, was an important supporter of the miasma theory. He believed that cholera was transmitted by air, and that there was a deadly concentration of miasmata near the River Thames' banks. Such a belief was in part accepted because of the general lack of air quality in urbanized areas.[2] The wide acceptance of miasma theory during the cholera outbreaks overshadowed the partially correct theory brought forth by John Snow that cholera was spread through water.