Rubuta ci gaba don wannan sakin layi - A cikin karni na 19, Biritaniya ita ce cibiyar ci gaban birane da sauri, kuma sakamakon haka, matsalolin kiwon lafiya da tsafta da yawa sun bayyana, alal misali barkewar cutar kwalara da annoba. Wannan ya haifar da Birtaniya ta taka muhimmiyar rawa a ci gaban lafiyar jama'a. Kafin a gano alaƙar da ke tsakanin gurɓataccen ruwan sha da cututtuka, kamar su kwalara da wasu cututtuka da ake samu ta ruwa, an yi amfani da ka'idar miasma don a ba da hujjar ɓarkewar waɗannan cututtuka. Ka'idar Miasma ita ce ka'idar cewa wasu cututtuka da cututtuka sune samfurori na "mummunan iska". Binciken likitan John Snow a Burtaniya a lokacin barkewar cutar kwalara ta 1854 Broad Street ya fayyace alaƙar da ke tsakanin cututtukan ruwa da gurɓataccen ruwan sha. Ko da yake ba a riga an ƙirƙiro ra'ayin ƙwayoyin cuta ba tukuna, abin da Snow ya lura ya sa ya yi watsi da ra'ayin ƙwayoyin cuta. Rubutun sa na 1855 "A kan Hanyar Sadarwar Cutar Cutar Cutar Cutar Cutar Cutar Cutar Cutar Cutar Cutar Cutar Cutar Cutar Cutar Cutar Cutar Cutar Cutar Cutar Cutar Cutar Cutar Cutar Cutar Cutar Cutar Cutar Cutar Cutar Cutar Cutar Cutar Cutar Cutar Cutar Cutar Cutar Cutar Cutar Cutar Cutar Cutar Cutar Cutar Cutar Cutar Cutar Cutar Cutar Cutar Cutar A lokacin annobar 1854, ya tattara kuma yayi nazarin bayanan da suka tabbatar da cewa mutanen da suka sha ruwa daga gurbataccen tushe kamar su Broad Street famfo
sun mutu ne daga cutar kwalara a mafi yawan wadanda suka samu ruwa a wasu wurare. Bayanansa sun shawo kan majalisa na gari don kashe famfon ruwa, wanda ya kawo karshen barkewar cutar.