st. louis missori topeka kansas watertown massachusettes harriman tennessee the city with the lowest particulate matter concentration in the air during 1990-1998 was

Hello. This question is incomplete because you forgot to show the graph that is part of the question and that is necessary for it to be answered.

The chart is attached below.

Watertown, Massachusettes

Explanation:

To answer this question you just need to read the information shown in the graphics. This way:

The blue dots within the graph represent the concentration of particulate material in the air during 1990-1998. Among these points, the one that represents the city of Watertown, Massachusettes is the one that represents the lowest concentration of these particles, which justifies the low number of relative mortality in that city in that same period.