What is similar between elements in horizontal rows in the periodic table?

A horizontal row on the Periodic Table is called a Period; and in the same Period, electrons fill the SAME valence shell. ... Full valence shells, i.e. the element has 2 OR 10 electrons, are stable electronic structure

Explanation:

they had the law tat factories that produces smoke cannot be built near residential buildings.

building of proper sewage system was done to ensure that the waste is carried away from the humans so that they do not get diseases from it.

also they built water systems to provide water in those areas which are drought prone.