Providence Air Quality Visualization

As for how to represent this data on a map. I was thinking about the detective crime scene in the TV show - Using red lines arranged on the map. And the density of the red line is an indicator of air quality: the denser the line, the lower the air quality. In terms of the color,  since air quality and the crime scenes investigation are related to human safety, I think this expression and red color which looks like blood are the best way to express it.

​

As can be seen from the picture, the redder the area, the worse the air quality.