Why do you think Sumerians thought that cleansing was necessary before entering shrines?

Because cleaning standards in Ancient Summer were not very high. Sanitation was not readily available for everyone. Besides, most people in Ancient Summer were farmers, working in the fields every day, where they would obviously get their clothes and body dirty.

Finally, a shrine is a place that every culture in the world deems sacred, and where people need to enter in a clean state of mind, and with clean clothes and body as well.

worldwide, 780 million people do not have access to an improved water source. an estimated 2.5 billion people lack access to improved sanitation (more than 35% of the world's population)

angel island immigration station was an immigration station located in san francisco bay which worked from 1910 to 1940. the majority of immigrants that got there were from the asian hemisphere, specifically from china, japan, russia, and south asia, being china the country from where more people arrived.

the number of foreigners arriving at it took the attention of americans who feared the new arrivals would take their jobs. the work opportunities were not abundant due to the economic comedown of 1870 and the asians, as newcomers, were willing to work for cheaper wages. soon they started to be seen as a threat, which led to an increased discrimination against the chinese - the biggest ethnicity arrived at this station until 1915 when japanese immigrants outnumbered them - being considered as unsuitable americans hence their looks and social situation.

at the station, the immigrant's detention may vary depending on how long the interrogation process took: it could be weeks, months, or even years.

finally, in 1940 an explosion destroyed administration building located on the island, so the united states government decided to stop the process.